1. Prepare the Chicken:

• Pat Dry: Pat the chicken breasts thoroughly dry with paper towels. This is key for getting a good sear.
• Create Pockets: Place a chicken breast flat on a cutting board. Hold your knife parallel to the cutting board and carefully make a deep slit or pocket along one long side of the chicken breast, cutting about three-quarters of the way through but not all the way. Be careful not to cut through the opposite side or the ends. Repeat with the remaining chicken breasts.
• Season: In a small bowl, mix together 1 teaspoon salt, 1/2 teaspoon black pepper, garlic powder, onion powder, and 1/2 teaspoon dried oregano. Season the inside and outside of each chicken breast generously with this mixture.
• Stuff the Chicken: Gently open the pocket of each chicken breast. If using, place 1-2 fresh basil leaves inside. Then, insert a slice or a few balls of the patted-dry fresh mozzarella into each pocket. Don’t overstuff, as the cheese will expand and ooze out excessively. Press the opening slightly to seal, or use a couple of toothpicks to secure the opening if needed (remember to remove them before serving!).
• Dredge (Optional): Lightly dredge the stuffed chicken breasts in the all-purpose flour, shaking off any excess. This helps create a golden-brown crust.

2. Make the Pomodoro Sauce:

• Sauté Aromatics: In a large, oven-safe skillet (cast iron or stainless steel is ideal) that can accommodate all chicken breasts without crowding, heat 2 tablespoons of extra virgin olive oil over medium heat. Add the minced garlic and red pepper flakes (if using) and sauté for about 1-2 minutes until fragrant. Be careful not to burn the garlic.
• Deglaze (Optional): If using, pour in the white wine and scrape up any browned bits from the bottom of the pan. Let it simmer for 1-2 minutes until it has reduced slightly.
• Add Tomatoes: Stir in the crushed tomatoes and tomato paste (if using).
• Season Sauce: Add the chopped fresh basil (reserving some for garnish), 1 teaspoon dried oregano, sugar (if using), 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Stir well to combine.
• Simmer: Bring the sauce to a gentle simmer, then reduce the heat to low and let it cook, stirring occasionally, for about 10-15 minutes to allow the flavors to meld. Taste and adjust seasoning if necessary.

3. Cook the Chicken:

• Preheat Oven: While the sauce is simmering, preheat your oven to 400°F (200°C).
• Sear Chicken: In a separate large skillet (or if your oven-safe skillet for the sauce is large enough and you temporarily remove the sauce, you can use that), heat 2 tablespoons of olive oil over medium-high heat. Once the oil is shimmering, carefully place the stuffed (and floured, if using) chicken breasts in the hot skillet. Sear for 3-4 minutes per side, until golden brown. Don’t overcrowd the pan; cook in batches if necessary. The chicken will not be cooked through at this point.
• Combine with Sauce: Carefully nestle the seared chicken breasts into the simmering Pomodoro sauce in the oven-safe skillet. If you used a separate skillet for searing, transfer the chicken to the skillet with the sauce. Spoon some of the sauce over the tops of the chicken.
• Bake: Transfer the oven-safe skillet to the preheated oven. Bake for 15-25 minutes, or until the chicken is cooked through (internal temperature reaches 165°F / 74°C in the thickest part of the chicken, not the cheese) and the mozzarella is melted and bubbly. The exact time will depend on the thickness of your chicken breasts.
• Rest: Remove the skillet from the oven. If you used toothpicks, carefully remove them. Let the chicken rest in the sauce for 5-10 minutes before serving. This allows the juices to redistribute, resulting in more tender chicken.

4. Garnish and Serve:

• Sprinkle with additional fresh chopped basil and freshly grated Parmesan cheese, if desired, just before serving.