Warming up with a bowl of French Onion Soup on a chilly evening is one of life’s simple pleasures. Recently, I decided to try my hand at making this classic comfort food at home, using the recipe you’re about to discover. Let me tell you, the aroma that filled my kitchen as the onions caramelized was simply divine. My family, usually a tough crowd to please when it comes to soups, devoured every last drop. The rich, deeply flavorful broth, the sweet caramelized onions, and that glorious, gooey cheese pull from the toasted bread – it was a culinary experience that transported us straight to a cozy Parisian bistro. This recipe isn’t just about following steps; it’s about creating a moment of warmth and deliciousness that everyone will love. Get ready to transform simple ingredients into a truly unforgettable French Onion Soup!

Ingredients

Crafting the perfect French Onion Soup hinges on the quality and balance of its ingredients. Each component plays a crucial role in building the layers of flavor that define this classic dish. Let’s delve into each ingredient and understand why it’s essential and how to choose the best for your soup.

1 tablespoon olive oil: Olive oil serves as the initial cooking medium, providing a neutral base for sautéing the onions and preventing them from sticking to the pot. Opt for a good quality extra virgin olive oil for a subtle fruity note, or a lighter olive oil if you prefer a more neutral flavor. While olive oil is traditional, you could also use other neutral oils like canola or vegetable oil if preferred, but olive oil adds a touch of Mediterranean flair.
3 pounds (1.36 kg) onions, approx. (about 5 or 6 medium onions): Onions are undeniably the star of the show in French Onion Soup. The type of onion you choose significantly impacts the final flavor profile. Yellow onions are the most commonly used and readily available, offering a balanced sweetness and savory depth when caramelized. However, for a sweeter soup, consider incorporating Vidalia or Walla Walla onions. For a more pungent and robust flavor, a mix of yellow and white onions can be interesting. The key is to ensure you have a substantial amount of onions – they reduce significantly during caramelization, becoming the heart and soul of the soup’s flavor. Don’t be tempted to skimp on the quantity; it’s the caramelized onions that truly make this soup exceptional.
2 tablespoons light brown sugar: Brown sugar is a crucial ingredient in achieving that deep, rich caramelization and beautiful color in the onions. The molasses in brown sugar enhances the sweetness and adds a subtle depth of flavor that white sugar simply can’t replicate. Light brown sugar is recommended for a balanced sweetness, but you could experiment with dark brown sugar for a richer, more intense molasses flavor. The sugar helps to draw out the natural sugars in the onions and encourages the Maillard reaction, the browning process that creates complex flavors.
1 1/2 teaspoons Worcestershire sauce: Worcestershire sauce is the secret umami weapon in this recipe, adding a savory depth that elevates the overall flavor profile. This fermented sauce is packed with complex flavors – tangy, sweet, salty, and umami – which complement the sweetness of the caramelized onions and the richness of the beef broth. If you don’t have Worcestershire sauce, you can substitute a teaspoon of soy sauce or balsamic vinegar, although the flavor will be slightly different. Vegetarians can ensure their Worcestershire sauce is anchovy-free, or use a vegetarian alternative.
2 cloves garlic, minced: Garlic adds a pungent and aromatic layer to the soup, balancing the sweetness of the onions and adding complexity. Freshly minced garlic is always preferred for the best flavor. Minced garlic is added towards the end of the onion caramelization process to prevent it from burning and becoming bitter. Don’t overcook the garlic; you want it to be fragrant and just slightly softened. For a milder garlic flavor, you can use roasted garlic instead.
1 tablespoon butter, optional: Butter is an optional but highly recommended addition to enhance the richness and velvety texture of the soup. Adding butter towards the end of the onion caramelization process contributes a luxurious mouthfeel and a subtle nutty flavor that complements the caramelized onions beautifully. Unsalted butter is recommended to control the overall saltiness of the soup. For a richer flavor, consider using European-style butter with a higher butterfat content. If you are dairy-free, you can omit the butter or use a plant-based butter alternative.
2 tablespoons all-purpose flour, optional: Flour is also an optional ingredient, used as a thickening agent to create a slightly richer and more substantial broth. All-purpose flour is the most common choice, but you can also use gluten-free flour blends if needed. The flour is briefly cooked with the onions and butter to create a roux, which helps to thicken the soup when the stock is added. If you prefer a lighter broth, you can omit the flour altogether. Ensure the flour is cooked for a minute or two to eliminate any raw flour taste.
1 cup (236.59 ml) wine, (sherry, marsala, or port are good choices), optional: Wine is another optional ingredient that adds depth and complexity to the broth. Sherry, Marsala, or Port are all excellent choices, each contributing a unique flavor profile. Dry sherry adds a nutty, slightly savory note, Marsala brings a rich, caramelized sweetness, and Port offers a fruity, slightly sweet complexity. The wine is added after the flour (if using) and deglazes the pot, lifting up any flavorful browned bits from the bottom. If you prefer not to use alcohol, you can substitute an equal amount of beef broth or a splash of balsamic vinegar for a touch of acidity. Cooking the wine for a few minutes allows the alcohol to evaporate, leaving behind its concentrated flavors.
8 cups (1.89 l) beef stock, (chicken or vegetable stock can be substituted): Beef stock forms the foundation of the French Onion Soup broth, providing a rich and savory base. High-quality beef stock is crucial for the best flavor. Homemade beef stock is ideal, but good quality store-bought beef stock works well too. Low-sodium beef stock is recommended to control the salt content, allowing you to adjust seasoning later. For a lighter flavor, you can substitute chicken stock, or for a vegetarian version, use vegetable stock. The choice of stock significantly impacts the overall flavor profile of the soup, so select one that you enjoy.
1 small bunch fresh thyme: Fresh thyme adds a delicate, earthy, and slightly lemony aroma to the soup. The thyme sprigs are added to the broth to infuse their flavor during simmering and then removed before serving. Fresh thyme is preferred for its brighter and more pronounced flavor, but you can substitute dried thyme if needed, using about 1 teaspoon of dried thyme for every tablespoon of fresh. Other herbs that complement French Onion Soup include bay leaf and rosemary.
1 bay leaf: Bay leaf is a subtle but essential aromatic ingredient that adds depth and complexity to the broth. It imparts a slightly woody and tea-like flavor that enhances the savory notes of the soup. Only one bay leaf is needed, as it can be quite potent. Remember to remove the bay leaf before serving the soup.
1 tablespoon kosher salt, (or to taste): Salt is crucial for seasoning and enhancing the flavors of all the ingredients. Kosher salt is recommended for its clean taste and ease of use. Start with the recommended amount and then adjust to taste. Remember that the saltiness of the beef stock can vary, so taste the soup and season accordingly. Salt not only enhances flavor but also draws out moisture from the onions during caramelization.
1/4 teaspoon black pepper: Black pepper adds a subtle warmth and spice to the soup, balancing the sweetness and richness. Freshly ground black pepper is always preferred for its brighter and more aromatic flavor. Adjust the amount of pepper to your preference. White pepper can be used as a substitute for a milder peppery note.
16 slices crusty French bread, toasted: Crusty French bread is essential for the classic French Onion Soup presentation and experience. A baguette or other crusty loaf works perfectly. The bread is toasted to provide a sturdy base for the cheese and to prevent it from becoming soggy in the soup. Toasting the bread also enhances its flavor and texture. You can toast the bread in the oven, under the broiler, or in a toaster.
1 cup (132 g) shredded Gruyere cheese: Gruyere cheese is the quintessential cheese for French Onion Soup. It has a nutty, slightly sweet, and complex flavor that melts beautifully and becomes wonderfully gooey and stretchy under the broiler. Gruyere cheese is essential for that classic cheesy topping and flavor. It provides the perfect balance of flavor and meltability.
1 cup (112 g) shredded mozzarella cheese: Mozzarella cheese is added to complement the Gruyere, providing extra meltiness and stretch. Low-moisture mozzarella is recommended to prevent the soup from becoming watery. Mozzarella has a milder flavor that allows the Gruyere to shine while contributing to the overall gooeyness of the cheese topping. The combination of Gruyere and mozzarella creates the perfect cheesy, bubbly topping for French Onion Soup.

Instructions

Creating authentic French Onion Soup is a rewarding culinary journey, and following these detailed instructions will guide you through each step to achieve a truly delicious result. Patience and attention to detail, especially during the caramelization process, are key to unlocking the rich flavors of this classic soup.

Heat the olive oil in a large, heavy-bottomed pot over medium heat. Select a large, heavy-bottomed pot, such as a Dutch oven or stockpot. The heavy bottom ensures even heat distribution and prevents scorching, which is crucial for caramelizing onions. Place the pot over medium heat and add the olive oil. Allow the oil to heat up gently; it’s ready when it shimmers slightly or when a drop of water flicked into the pot sizzles.
Halve, peel, and slice the onions thinly, then add them to the pot and stir. Prepare the onions by halving them lengthwise, peeling off the outer layers, and then slicing them thinly, from root to stem. Aim for uniform slices, about 1/8 to 1/4 inch thick, as this ensures even cooking and caramelization. Adding thinly sliced onions to the pot will maximize surface area for caramelization. Once sliced, add all the onions to the pot with the heated olive oil. Stir immediately to coat the onions evenly with the oil and prevent them from sticking to the bottom of the pot.
Add the brown sugar and Worcestershire sauce, and continue to cook, stirring every few minutes, until the onions become a deep golden brown. This is the most crucial step – caramelizing the onions. Add the brown sugar and Worcestershire sauce to the pot with the onions. Stir well to combine and ensure the sugar and sauce are evenly distributed. Reduce the heat to medium-low or low if the onions are browning too quickly. The goal is to caramelize the onions slowly and gently, drawing out their natural sugars and developing deep, complex flavors. This process will take time, typically 30-45 minutes or even longer depending on the heat and the type of onions. Stir the onions every few minutes to prevent sticking and burning, scraping up any browned bits from the bottom of the pot. As the onions cook, they will soften, release moisture, and gradually turn from translucent to golden brown, and eventually to a deep, rich golden brown. Patience is key here; resist the urge to rush the caramelization process. The deeper the color, the richer the flavor of your soup will be.
Stir in the garlic, cooking until fragrant. Once the onions have reached a deep golden brown color, add the minced garlic to the pot. Stir the garlic into the caramelized onions and cook for about 1-2 minutes, or until fragrant. Be careful not to burn the garlic, as it can become bitter. Cooking the garlic briefly at this stage releases its aromatic oils and adds a pungent layer of flavor to the soup.
Add the butter to the pot, sprinkle in the flour, and stir everything together. If using butter and flour (optional), add the butter to the pot and let it melt into the onions and garlic. Once melted, sprinkle the flour evenly over the mixture. Stir continuously to combine the butter and flour, creating a roux. Cook the roux for about 1-2 minutes, stirring constantly, to cook out the raw flour taste. This step helps to thicken the soup slightly and adds richness.
Pour in the wine and stir, scraping any browned bits from the bottom of the pot with your spoon. If using wine (optional), pour it into the pot. Immediately use a wooden spoon or spatula to scrape up any browned bits (fond) that have accumulated on the bottom of the pot. These browned bits are packed with flavor and deglazing with wine helps to incorporate them into the soup. Stir well to combine the wine with the onion mixture and cook for about 2-3 minutes, allowing the alcohol to evaporate and the wine to reduce slightly.
Stir in the stock, add the herbs, and allow the soup to come to a simmer. Pour the beef stock into the pot with the onion mixture. Add the fresh thyme sprigs and bay leaf to the pot. Stir well to combine all the ingredients. Bring the soup to a simmer over medium heat, then reduce the heat to low, cover the pot, and simmer gently for at least 15-20 minutes, or longer for a more developed flavor. Simmering allows the flavors to meld together and deepen.
Season with salt and pepper. After simmering, season the soup with kosher salt and black pepper to taste. Start with the recommended amounts and then adjust according to your preference. Taste the soup and add more salt and pepper as needed. Remember that the saltiness of the stock and cheese can vary, so season gradually and taste frequently.
Remove the thyme stems and bay leaf, then ladle the soup into heat-safe bowls or crocks, and top with toasted bread and cheese. Before serving, remove the thyme stems and bay leaf from the soup using tongs or a slotted spoon. Ladle the hot soup into heat-safe bowls or oven-safe crocks. Place 2 slices of toasted French bread on top of each bowl of soup, ensuring they are slightly submerged in the broth. Generously top each bread slice with shredded Gruyere cheese and then sprinkle with shredded mozzarella cheese.
Melt the cheese under the broiler, until browned and bubbly, and serve. Preheat your broiler to high. Place the bowls of soup on a baking sheet and carefully place them under the broiler. Broil for 2-3 minutes, or until the cheese is melted, bubbly, and nicely browned. Watch closely to prevent the cheese from burning. Alternatively, you can use a kitchen torch to melt and brown the cheese. Once the cheese is perfectly melted and browned, carefully remove the bowls from under the broiler. Let them cool slightly for a minute or two before serving. Serve immediately while the cheese is hot, gooey, and stretchy, and the soup is warm and comforting.

Nutrition Facts

Understanding the nutritional profile of your French Onion Soup can help you make informed choices about your meal. Please note that these are approximate values and can vary based on specific ingredients and serving sizes.

Servings: 8

Approximate Calories per Serving: 350-450 calories (This is an estimate and can vary based on cheese quantity, bread size, and use of optional ingredients like butter, flour, and wine)

Typical Nutritional Breakdown per Serving (Approximate):

Protein: 20-25g
Carbohydrates: 30-35g
Fat: 15-20g
Saturated Fat: 8-10g
Cholesterol: 50-70mg
Sodium: 800-1000mg (can be adjusted by using low-sodium broth and controlling salt)
Fiber: 3-5g
Sugar: 10-15g (naturally occurring from onions and added brown sugar)

Nutritional Considerations:

Calories: French Onion Soup can be moderately calorie-dense, primarily due to the cheese and bread.
Sodium: The sodium content can be relatively high, mainly from the beef stock, Worcestershire sauce, and cheese. Using low-sodium broth and controlling added salt can help reduce sodium levels.
Fat: The fat content comes from olive oil, butter (if used), and cheese. While some fat is essential, be mindful of saturated fat intake.
Protein: The soup provides a good source of protein, mainly from the beef stock and cheese.
Carbohydrates: Carbohydrates come from onions, bread, and added sugar.
Vitamins and Minerals: French Onion Soup provides some vitamins and minerals, depending on the ingredients and stock used. Onions are a source of Vitamin C and fiber. Beef stock can provide B vitamins and minerals.

Note: These are estimates. For precise nutritional information, use a nutrition calculator app and input the exact ingredients and quantities you use. You can also modify the recipe to make it lighter by using less cheese, omitting butter and flour, and using low-sodium broth.

Preparation Time

Efficient preparation is key to streamlining the French Onion Soup cooking process. While the caramelization of onions takes time, proper planning can make the overall experience smoother and more enjoyable.

Prep Time: 35 minutes

This prep time includes:

Onion Preparation (20 minutes): Peeling and thinly slicing approximately 3 pounds of onions takes the most time. Using a sharp knife and efficient slicing technique will help speed up this process. You can also use a mandoline for uniform slices, but be cautious and use a finger guard.
Garlic Mincing (5 minutes): Mincing 2 cloves of garlic is a quick task.
Herb Preparation (5 minutes): Gathering and preparing the fresh thyme and bay leaf.
Cheese Shredding (5 minutes): Shredding Gruyere and mozzarella cheese. Pre-shredded cheese can save a few minutes, but freshly shredded cheese melts better.

Cook Time: 20 minutes

This cook time encompasses:

Initial Sautéing and Caramelization (30-45 minutes – part of total cooking process, but actively cooking during this time): While caramelizing onions takes a significant amount of time, it’s a relatively hands-off process, requiring occasional stirring. This time is factored into the overall cook time, but it’s more about letting the onions slowly transform rather than active cooking for the entire duration.
Adding Garlic and Optional Butter/Flour/Wine (5 minutes): These steps are quick and add minimal time.
Simmering in Stock (15-20 minutes): Simmering allows the flavors to meld and deepen.
Broiling Cheese (2-3 minutes): Broiling the cheese is a fast final step.

Total Time: 55 minutes (excluding onion caramelization time which runs concurrently with prep)

The total time of 55 minutes represents the active hands-on time, excluding the longer duration of onion caramelization. It’s important to note that while the active prep and cook time is around 55 minutes, the overall process from start to finish, including the caramelization of onions, can take closer to 1.5 – 2 hours. However, much of the caramelization time is hands-off.

Tips to Optimize Prep Time:

Efficient Onion Slicing: Practice your knife skills or use a mandoline (with caution) for faster onion slicing.
Pre-Shredded Cheese: Using pre-shredded cheese can save a few minutes.
Organization (Mise en Place): Having all ingredients prepped and measured before starting to cook significantly speeds up the process.
Multitasking: While the onions are caramelizing, you can prepare the bread, shred the cheese, and gather other ingredients to maximize efficiency.

How to Serve

French Onion Soup is a dish that can be elevated by thoughtful serving suggestions, enhancing the overall dining experience. Here are some ideas on how to serve this classic soup:

Classic Crock Presentation: Serve the soup in oven-safe crocks or bowls. This is the traditional and most visually appealing way to serve French Onion Soup. The crocks help keep the soup warm and are perfect for broiling the cheese topping.
Garnish with Fresh Thyme: A sprig of fresh thyme placed on top of the cheesy crust adds a touch of elegance and reinforces the herbaceous notes in the soup.
Accompaniments:
- Side Salad: A simple green salad with a light vinaigrette provides a refreshing contrast to the rich soup.
- Crusty Bread: Serve extra crusty French bread or baguette slices on the side for dipping and soaking up the delicious broth.
- Cheese Board: A small cheese board with Gruyere, Swiss, or other complementary cheeses can enhance the cheesy experience.
Wine Pairing:
- Red Wine: A medium-bodied red wine like Beaujolais, Pinot Noir, or Merlot complements the richness of the soup.
- White Wine: A dry white wine with good acidity, such as Sauvignon Blanc or Chardonnay, can also pair well.
- Sherry or Port: If you used Sherry or Port in the soup, serving a glass of the same wine alongside can create a harmonious pairing.
Occasions:
- Cozy Nights: French Onion Soup is perfect for a comforting and warming meal on a cold evening.
- Dinner Parties: It’s an elegant and impressive starter for a dinner party.
- Holiday Meals: French Onion Soup can be a delightful addition to holiday menus, especially during the fall and winter seasons.
- Casual Lunches: Serve smaller portions for a satisfying and flavorful lunch.
Vegetarian/Vegan Adaptations (Serving Considerations):
- Vegetarian: Ensure you use vegetable broth and vegetarian Worcestershire sauce. Continue to use Gruyere and mozzarella cheese or explore vegetarian cheese alternatives.
- Vegan: Use vegetable broth, vegan Worcestershire sauce, vegan butter (optional), and vegan cheese alternatives that melt well. You can also skip the cheese topping entirely and focus on the rich broth and caramelized onions. Consider topping with toasted breadcrumbs or a swirl of vegan cream for richness.
Serving Temperature: Serve French Onion Soup immediately after broiling the cheese, while it’s hot and the cheese is melted and gooey. The contrast between the hot soup and the cheesy topping is part of the enjoyment.

Additional Tips for Perfect French Onion Soup

Elevate your French Onion Soup from good to extraordinary with these five essential tips, gleaned from years of soup-making experience:

Patience is Paramount for Caramelizing Onions: The single most crucial element for exceptional French Onion Soup is deeply caramelized onions. Don’t rush this process. Low and slow cooking is key. Resist the urge to turn up the heat to speed things up, as this can result in burnt onions that taste bitter rather than sweet and savory. Aim for a gentle, even caramelization over at least 30-45 minutes, stirring occasionally and scraping the bottom of the pot to prevent sticking. The onions should transform into a rich, mahogany brown color and have a sweet, almost jammy flavor. This depth of flavor is the foundation of a truly authentic French Onion Soup.
Use High-Quality Beef Broth (or Homemade if Possible): Since the broth is the liquid base of the soup, its quality significantly impacts the final taste. Opt for a high-quality store-bought beef broth with a rich, deep flavor. Low-sodium broth is recommended to control the salt level. Even better, consider making your own beef broth from scratch. Homemade broth has a depth and richness that store-bought versions often lack. Using a flavorful broth ensures a more robust and satisfying soup. If using store-bought, taste it before adding it to the soup and choose one that you find flavorful and not overly salty or bland.
Don’t Skimp on the Cheese—and Choose the Right Kinds: The cheesy topping is an integral part of French Onion Soup. Be generous with the cheese! A good layer of cheese that melts beautifully and creates that signature gooey pull is essential. Gruyere cheese is the classic choice for its nutty, complex flavor and excellent melting properties. Adding mozzarella, as suggested in the recipe, enhances the meltiness and stretch. Consider adding a third cheese like provolone or Swiss for even more flavor complexity. Ensure the cheese is shredded and evenly distributed over the bread to create a uniformly melted and browned crust.
Toast the Bread Properly for Texture and Flavor: The toasted bread provides a crucial textural contrast to the soup and serves as the base for the cheesy topping. Don’t use soft, untoasted bread, as it will become soggy and disintegrate in the soup. Use crusty French bread or baguette slices and toast them until they are golden brown and crisp. Toasting the bread not only prevents sogginess but also enhances its flavor and adds a pleasant crunch. You can toast the bread in the oven, under the broiler, or even in a toaster. For extra flavor, lightly brush the bread with olive oil or garlic butter before toasting.
Make it Ahead of Time for Even Richer Flavor (Especially the Onion Base): French Onion Soup is a fantastic make-ahead dish. In fact, the flavor often improves after it sits for a day or two in the refrigerator, as the flavors meld and deepen. You can caramelize the onions and prepare the broth base a day or two in advance. Store the caramelized onions and broth separately in airtight containers in the refrigerator. When ready to serve, simply reheat the broth, assemble the soup in bowls, top with toasted bread and cheese, and broil. Making the onion base ahead of time not only saves time on the day of serving but also allows the caramelized onion flavor to become even more concentrated and delicious.

FAQ Section – Ingredients

Navigating the ingredient list for French Onion Soup can sometimes raise questions. Here are answers to five frequently asked questions specifically about the ingredients in this recipe:

Q1: Can I use different types of onions for French Onion Soup?

A: Absolutely! While yellow onions are the most traditional and widely used, you can definitely experiment with different types of onions or a combination for nuanced flavor profiles. Sweet onions like Vidalia or Walla Walla will result in a sweeter soup. White onions offer a sharper, more pungent flavor. Red onions can add a beautiful color and a slightly milder taste when caramelized. For a truly complex flavor, try a mix of yellow and sweet onions, or even incorporate a small amount of shallots or leeks for added depth. The key is to use a substantial amount of onions, regardless of the type, as they are the star ingredient and reduce significantly during caramelization.

Q2: Is it possible to make a vegetarian or vegan French Onion Soup?

A: Yes, it’s entirely possible and delicious! For a vegetarian version, simply substitute beef stock with vegetable broth. Ensure your Worcestershire sauce is vegetarian-friendly (many are not due to anchovies) or use a vegetarian alternative. Continue to use Gruyere and mozzarella cheese, or explore vegetarian cheese options that melt well. For a vegan French Onion Soup, use vegetable broth, vegan Worcestershire sauce or soy sauce for umami, and vegan butter as an optional richness enhancer. For the cheesy topping, explore vegan cheese shreds that are designed to melt, or get creative with a topping of toasted breadcrumbs or a creamy white bean puree for richness and texture in place of cheese. The caramelized onions and flavorful broth will still be the stars of the dish, even without beef broth or dairy cheese.

Q3: What can I use if I don’t have wine for the soup?

A: If you prefer not to use wine or don’t have any on hand, there are several excellent substitutes that can still add depth and complexity to your French Onion Soup. The best non-alcoholic substitute is to simply use more beef broth (or vegetable broth for vegetarian). You can also add a splash of balsamic vinegar or red wine vinegar to the soup for a touch of acidity and depth, mimicking some of the wine’s characteristics. Another option is to use a small amount of grape juice or cranberry juice (unsweetened) for a subtle sweetness and fruitiness similar to Port wine. Remember that wine adds a layer of flavor, but a well-made French Onion Soup can still be delicious without it by focusing on deeply caramelized onions and a flavorful broth.

Q4: Can I use dried thyme instead of fresh thyme?

A: Yes, you can substitute dried thyme for fresh thyme if needed, although fresh thyme will provide a brighter and more pronounced flavor. When substituting dried herbs for fresh, the general rule is to use about one-third the amount, as dried herbs are more concentrated in flavor. So, if the recipe calls for 1 small bunch of fresh thyme, you would use approximately 1 teaspoon of dried thyme. Add the dried thyme at the same time you would add fresh thyme, during the simmering stage. Keep in mind that fresh thyme has a more delicate and lemony aroma, while dried thyme has a more robust and earthy flavor.

Q5: Are there other cheeses I can use besides Gruyere and mozzarella?

A: Absolutely! While Gruyere and mozzarella are a classic and delicious combination, you can definitely experiment with other cheeses to create different flavor profiles for your French Onion Soup topping. Excellent alternatives or additions include: Swiss cheese (similar to Gruyere, nutty and melts well), Emmental (another Swiss-style cheese, slightly milder than Gruyere), Comté (a French cheese with nutty and fruity notes, similar to Gruyere but often more complex), provolone (melts beautifully and has a slightly sharper flavor), and even Parmesan cheese (adds a salty, savory, and umami kick – use sparingly as it’s stronger in flavor). You can use a single cheese or create your own blend of cheeses to customize the flavor and meltiness of your cheesy topping. Consider a combination of a flavorful cheese like Gruyere or Comté with a good melting cheese like mozzarella or provolone for the best results.