Cut the sub roll in half but not all the way through the roll. Spread one or two tablespoons of sauce on roll. Add 3-4 slices of eggplant parmesan. Spread another tablespoon of sauce onto the eggplant. Add 2 tablespoons of shredded mozzarella to top (more if you like). Place the sub on a baking sheet and heat in the broiler until cheese is melted.