Set up a line of 3 bowls or wide plates. Place ½ cup of grated Parmesan in a large plate or bowl. In the second medium bowl, whisk the egg. In the third bowl mix together bread crumbs, Italian seasoning, garlic powder, salt, and pepper.
Bread the Chicken: Dip chicken breasts in the Parmesan bowl first, and coat on both sides. Then, transfer coated chicken and dip in egg bowl on both sides. Last, dip both sides of chicken in bread crumbs mixture in the third bowl. Evenly coat and pack breadcrumbs lightly with your hand. Shake off any excess breading and repeat with the remaining chicken.
Sear the Chicken: Heat olive oil in a large cast iron skillet or pan and brown chicken for 3 minutes on each side, fora total of 6 minutes for both sides. I browned 2 chickens at a time.
Bake Chicken: Preheat oven at 375 F. Lay browned chicken in the same oven proof cast iron skillet (or a baking dish). Layer chicken with mozzarella slices. Then add marinara sauce over top. Scatter shredded Mozzarella and remaining ½ cup of Parmesan on top of Marinara. Bake for 30 minutes until sauce is bubbling, about 30 minutes.
Sprinkle with fresh basil and serve with spaghetti.