Step 1: Prepare the Chicken and Make the Herb Oil
Preheat your oven to 400°F (200°C). Pat the chicken breasts completely dry with paper towels. In a small bowl, combine 2 tablespoons of the olive oil, the minced garlic, chopped rosemary, thyme, oregano, salt, black pepper, and red pepper flakes (if using). Stir to form a loose paste. Rub this herb-garlic oil all over both sides of each chicken breast, ensuring they are fully coated.

Step 2: Sear the Chicken (Optional but Recommended)
Heat the remaining 1 tablespoon of olive oil in a large oven-safe skillet (like cast iron) over medium-high heat. Once hot, add the chicken breasts and sear for 2-3 minutes per side, just until they develop a golden-brown crust. They do not need to be cooked through. This step adds incredible flavor. If your skillet is not oven-safe, sear the chicken and then transfer it to a 9×13-inch baking dish.

Step 3: Assemble the Bake
If you seared in an oven-safe skillet, leave the chicken in the skillet. If using a baking dish, arrange the chicken in a single layer. Surround and tuck the thick tomato slices around and slightly under the chicken pieces. Season the tomatoes lightly with a pinch of salt and pepper.

Step 4: Bake
Transfer the skillet or baking dish to the preheated oven. Bake for 15 minutes.

Step 5: Add the Cheese and Finish Baking
After 15 minutes, remove the dish from the oven. Top each chicken breast and the surrounding tomatoes with slices of fresh mozzarella cheese. Scatter the ¼ cup of fresh basil leaves over everything. Return to the oven and bake for an additional 5-10 minutes, or until the chicken is cooked through (internal temperature of 165°F / 74°C) and the mozzarella is melted and bubbly.

Step 6: Prepare the Balsamic Glaze
While the chicken bakes, make the glaze. In a small saucepan, combine the balsamic vinegar, honey (or brown sugar), and optional minced garlic. Bring to a simmer over medium heat, then reduce heat to medium-low. Simmer gently, stirring occasionally, for 8-12 minutes, until the mixture has reduced by about half and coats the back of a spoon. It will thicken further as it cools. Remove from heat. (If using store-bought glaze, simply warm it slightly for easier drizzling).

Step 7: Glaze, Garnish, and Serve
Once the chicken is out of the oven, immediately drizzle the warm balsamic glaze generously over the entire dish. Finish with a sprinkle of flaky sea salt, some freshly cracked black pepper, and a final flourish of extra torn fresh basil leaves. For a touch of luxury, add a light drizzle of your best extra virgin olive oil.

Step 8: Rest and Serve
Let the bake rest for 5 minutes before serving. This allows the juices to redistribute in the chicken. Serve directly from the skillet or baking dish, ensuring each portion gets plenty of chicken, melted cheese, tomatoes, and glaze.