Creating amazing meatball subs can be a simple process with these straightforward steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Mix Meatball Ingredients: In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, parsley, garlic, egg, salt, pepper, and Italian seasoning. Mix until just combined.
3. Form Meatballs: Shape the mixture into meatballs, about 1 inch in diameter.
4. Bake Meatballs: Place the meatballs on a greased baking sheet. Bake for 15-20 minutes or until they are browned and cooked through.
5. Heat Marinara Sauce: While the meatballs are baking, heat the marinara sauce in a saucepan over medium heat. Add the baked meatballs to the sauce and simmer for a few minutes.
6. Prepare Sub Rolls: Cut the sub rolls in half and place them on a baking sheet.
7. Fill Rolls: Spoon a few meatballs along with the marinara sauce into each sub roll, making sure they’re well-covered.
8. Add Cheese: Sprinkle shredded mozzarella cheese generously over the top of each filled sub.
9. Melt Cheese: Place the filled rolls back into the oven for 5-10 minutes or until the cheese is bubbly and golden.
10. Garnish and Serve: Remove from the oven, garnish with extra parsley if desired, and serve hot!

These simple steps will lead you to create mouthwatering meatball subs that are sure to impress.