01 - Preheat oven to 400°F. Lightly coat a 9×13-inch baking dish with 1 tablespoon of the olive oil, ensuring an even film across the bottom and sides.
02 - Spread the sliced red, yellow, and green bell peppers along with the red onion in an even layer across the prepared baking dish. Drizzle with the remaining 1 tablespoon of olive oil, then sprinkle with half of the salt, black pepper, Italian seasoning, and smoked paprika. Toss gently until all vegetables are evenly coated.
03 - Pat the chicken breasts thoroughly dry with paper towels. Combine the remaining halves of the salt, black pepper, Italian seasoning, and smoked paprika, then rub the mixture evenly over both sides of each breast. Lay the seasoned chicken on top of the bed of vegetables in the baking dish.
04 - Scatter the minced garlic evenly over the chicken breasts and surrounding vegetables.
05 - Cover the baking dish tightly with aluminum foil and place in the center of the oven. Bake for 20 minutes to allow the chicken to cook through gently while the vegetables soften and release their juices.
06 - Carefully remove the foil. Sprinkle the shredded mozzarella and grated Parmesan evenly over each chicken breast. Return the dish to the oven uncovered and bake for an additional 10 minutes, or until the chicken reaches an internal temperature of 165°F and the cheese is fully melted with golden-brown spots on top.
07 - Remove the dish from the oven and let the chicken rest for 5 minutes to allow the juices to redistribute. Serve each breast over a portion of the roasted peppers and onions.