Preheat oven to 350.
Make Chicken parmesan, if you haven't already. Can use frozen breaded chicken breasts. If so, bake 'em according to directions.
Open the hoagie bun. Put a chicken parmesan on it. Top with sauce. Top that with mozzarella cheese. Close the hoagie bun.
Spray a sheet of aluminum foil lightly with cooking spray. Put the sandwich on top. Wrap it.
Put on a cookie sheet. Repeat for as many sandwiches as you need.
Bake for 30 minutes (maybe a little less if you just baked the chicken).
Unwrap. Serve. Eat.