Start by pounding your chicken breasts to an even thickness. This helps them cook evenly and stay juicy. I like to season both sides lightly with salt and pepper before dipping them.
Mix breadcrumbs, Parmesan, garlic powder, Italian seasoning, salt, and pepper in a shallow dish. Beat the egg in a separate bowl, then dip each chicken breast in the egg and coat it thoroughly with the breadcrumb mixture.
Place the coated chicken in a greased baking dish. Bake at 400°F (200°C) for about 20 minutes until the chicken is cooked through and golden brown. I always check with a meat thermometer to make sure it hits 165°F.
Remove the chicken from the oven and spoon marinara sauce over each piece. Sprinkle shredded mozzarella on top and bake for another 5 minutes until the cheese is melted and bubbly.
Finish with fresh basil leaves if desired. Let the chicken rest for a few minutes before serving to lock in the juices.