Add all the sauce ingredients to a slow cooker.
Cook on low at least 3 to 4 hours.
While sauce is cooking, mix the ground beef, Parmesan cheese, pepper, salt, bread crumbs, and eggs.
Use an ice cream scoop and place the meatballs on a large baking sheet that has been lightly sprayed with a cooking spray.
Bake the meatballs at 400 degrees for 20 minutes.
Remove the meatballs from the oven and place them into the slow cooker with spaghetti sauce.
When you get ready for your cheesy meatball sub:
Add a layer of Mozzarella cheese to the bottom of the sub roll.
And,Add the meatballs and spaghetti sauce on top of the Mozzarella cheese.
Plus, Add additional cheese on top of the meatballs