01 - Preheat the oven to 400°F. Lightly grease a large baking dish with cooking spray or a thin layer of olive oil.
02 - Spread the sliced red, yellow, and green bell peppers along with the sliced red onion evenly across the bottom of the prepared baking dish. Drizzle with 1 tablespoon of olive oil, sprinkle with half the salt and black pepper, and toss to coat evenly.
03 - Place the chicken breasts on top of the seasoned vegetables. Brush the chicken with the remaining 1 tablespoon of olive oil, rub the minced garlic over each breast, and season generously with smoked paprika, dried Italian herbs, and the remaining salt and black pepper.
04 - Sprinkle the shredded mozzarella and grated Parmesan cheeses evenly over the chicken breasts and surrounding vegetables, ensuring full coverage for a golden, bubbly finish.
05 - Bake uncovered for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the cheese is melted, golden, and bubbly on top.
06 - Remove from the oven and let the dish rest for 5 minutes to allow the juices to redistribute. Serve hot, garnished with fresh herbs if desired.