Heat oven to 400º F. Season the chicken with ½ teaspoon salt and ¼ teaspoon pepper.
Place the flour and eggs in separate shallow bowls; in a third shallow bowl, combine the bread crumbs and Parmesan. Coat the chicken with the flour, then dip in the eggs (letting any excess drip off), then coat with the bread crumb mixture, pressing gently to help it adhere.
Heat the oil in a large skillet over medium-high heat. Cook the chicken in batches until golden brown, about 2 minutes per side.
Pour the marinara sauce into a large, shallow baking dish. Top with the chicken and mozzarella.
Bake until bubbling and golden brown, 20 to 25 minutes.