Pound chicken to ½-inch thickness. Season with salt and pepper.
Prepare dredging stations: flour, egg wash, and breadcrumb-Parmesan mix.
Coat chicken in flour, dip in egg, then coat with breadcrumb mixture.
Heat oil in a skillet and fry chicken until golden brown, ~4-5 mins per side.
Preheat oven to 450°F (230°C).
Layer marinara sauce in a baking dish, place chicken, add more sauce, and top with mozzarella and Parmesan.
Bake for 10-15 minutes until cheese melts and bubbles.
Rest for a few minutes before serving.