In a large bowl, mix the ground beef, Italian breadcrumbs, Parmesan Cheese, egg, oregano, basil, onion powder, garlic powder, salt, and pepper. Roll the mixture into 1-inch meatballs.
In a large skillet over medium heat, brown the meatballs on all sides. Drain any excess grease. Add the marinara sauce to the skillet with the meatballs and simmer over medium-low heat for 15 minutes.
While the meatballs are simmering, split, butter, and toast the sub rolls under the broiler.
Spread half of the cheese over the bottom of the rolls. Place 5 meatballs in each roll and top with the remainder of the cheese. Broil the sandwiches just until the cheese is melted and lightly browned.
If desired, sprinkle with Parmesan cheese and chopped parsley. Serve promptly.
