Cut the chicken breasts into thin cutlets.
In a shallow bowl, whisk together the flour, salt, and pepper.
In another shallow bowl, whisk together the milk and eggs.
In a third shallow bowl, place the breadcrumbs.
Dip the chicken cutlets in the flour mixture, then dip them in the milk mixture, and then coat them in the breadcrumbs.
Heat the olive oil in a large skillet over medium heat.
Add the chicken cutlets to the skillet and cook for 3-4 minutes per side, or until golden brown and cooked through.
Spread 1/4 cup of marinara sauce on each hamburger bun bottom.
Top each bun with a chicken cutlet, 1/4 cup of marinara sauce, 1 tablespoon of mozzarella cheese, and 1 tablespoon of chopped basil (optional).
Broil the sandwiches for 1-2 minutes, or until the cheese is melted and bubbly.
Sprinkle each sandwich with 1 tablespoon of Parmesan cheese (optional).
Serve immediately.