01 - Preheat oven to 400°F. Lightly grease a large 9x13-inch baking dish with 1 tablespoon of the olive oil, ensuring an even coating across the bottom and sides.
02 - Arrange 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 and sprinkle with half of the salt, black pepper, Italian seasoning, and smoked paprika. Toss the vegetables gently to coat evenly.
03 - Pat the chicken breasts dry with paper towels. Season both sides of each breast with the remaining salt, black pepper, Italian seasoning, and smoked paprika, pressing the spices gently into the meat.
04 - Place the seasoned chicken breasts on top of the vegetable bed in the baking dish. Scatter the minced garlic evenly over the chicken and surrounding vegetables.
05 - Cover the baking dish tightly with aluminum foil and bake for 20 minutes, allowing the chicken to cook through and the vegetables to soften in the steam.
06 - Remove the foil and sprinkle the shredded mozzarella and grated Parmesan cheeses evenly over each chicken breast. Return the dish to the oven uncovered and bake for an additional 10 minutes, or until the chicken registers 165°F internally and the cheese is melted, bubbly, and golden.
07 - Remove the baking dish from the oven and let the chicken rest for 5 minutes before serving. This allows the juices to redistribute for more tender, flavorful results. Serve each breast over a bed of the roasted peppers and onions.