Preheat the oven to 375°F (190°C) and lightly grease a 9×13-inch baking dish.
Season the chicken with salt, pepper, garlic powder, and Italian seasoning.
Heat olive oil in a large skillet over medium heat. Sear the chicken for 2–3 minutes per side until lightly golden.
Transfer the chicken to the prepared baking dish.
Scatter the halved tomatoes and minced garlic around the chicken.
Top each chicken breast with mozzarella cheese.
Bake the Caprese Chicken Casserole uncovered for 25–30 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).
Remove from the oven and garnish with fresh basil.
Drizzle with balsamic glaze and sprinkle with red pepper flakes if desired.
Serve immediately with pasta, rice, mashed potatoes, or a fresh green salad.