Mix ground beef, ground sausage, minced onion, garlic salt, Italian seasoning and black pepper in large bowl.
Shape into 18 (1 inch) meatballs.
Melt butter or heat olive oil in a large skillet over medium heat, and brown the exterior of the meatballs, flipping and turning them until fully browned and partially cooked through
Pour Manwich Original Sloppy Joe Sauce sauce over top, and let simmer.
Simmer 10-15 minutes, until meatballs are cooked through.
Preheat oven to broil.
Evenly distribute meatballs into sub rolls, and top with a sprinkle of cheese.
Broil 1-2 minutes until cheese is melted
Garnish with fresh parsley