Preheat oven to 425°F and line a baking sheet with foil.
Place the chicken breast halves between plastic wrap and pound to even thickness.
Dredge each piece first in flour, then dip into beaten eggs, and coat in a mixture of breadcrumbs, Parmesan, garlic powder, salt, and pepper.
Heat olive oil in a skillet and brown the chicken for 2-3 minutes per side.
Place browned chicken on the baking sheet, top each with marinara and a slice of mozzarella.
Bake for 10-12 minutes or until cheese is melted and bubbly.
Toast the sandwich buns and assemble the sandwiches with chicken and optional basil.