Begin by preheating your oven to 375°F and setting the rack in the middle. Season both sides of each chicken breast with garlic powder, salt, and pepper to build a flavorful base.
Warm the olive oil in a skillet over medium-high heat. Sear the chicken breasts for about five minutes per side until golden. This step locks in moisture and enhances the taste, then transfer the chicken to your baking dish.
Pour marinara evenly over the chicken, ensuring each piece is well coated. Sprinkle freshly grated Parmesan first, followed by a generous layer of mozzarella.
Bake uncovered for about 20 minutes (slightly less if using small chicken breasts). Once done, broil for a few minutes until the cheese turns bubbly and lightly golden. Let the dish rest for five minutes before serving.