Preheat your oven to 400°F (200°C).
Grease a baking dish with olive oil or cooking spray and set aside.
In a shallow bowl, combine the breadcrumbs, grated Parmesan cheese, garlic powder, Italian seasoning, salt, and black pepper.
In another shallow bowl, whisk the egg until fully beaten.
Dip each chicken breast into the egg, allowing any excess to drip off, then coat it in the breadcrumb mixture, pressing the crumbs onto the chicken to adhere well.
Place the coated chicken breasts in the prepared baking dish.
Bake in the preheated oven for 20 minutes, or until the chicken is cooked through and has an internal temperature of 165°F (75°C).
Remove the chicken from the oven and spoon the marinara sauce evenly over each piece.
Sprinkle the shredded mozzarella cheese on top of the sauce.
Return the dish to the oven and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it rest for a few minutes before serving.