Preheat oven to 350 degrees.
Split the sub rolls down the middle and spread pizza sauce evenly between each piece.
Top the bottom pieces of the sub rolls with mozzarella and pepperoni. Add extra toppings if using. Top with Parmesan.
Place the top halves of the sub rolls over the sandwich.
Stir together the butter, garlic, onion powder, and parsley and spoon over the tops of the sandwiches.
Bake for 15 minutes or until the bread is toasty and the cheese has melted.
Serve immediately.
