I learned to make meatball subs at a friend's apartment back in college. She taught me this trick of stuffing cubes of mozzarella inside the raw meatballs before frying them up on the stove. When they were done, you would bite into this thing and cheese would just ooze out. So so very good.
Over the years I have tried to make them that way, but somehow the cheese would always sneak out during baking and when you bite into them all you are left with is a cavern of disappointment where the cheese once was. I think it was the baking that led me astray, actually. Frying crisps up the edges so nothing can escape, I suppose. Nevertheless, I cannot bring myself to fry meatballs because they make such a mess of the cooktop, whereas baking them avoids all that and you simply pour off the grease afterwards. So when the weather turned chilly recently, it seemed about time to treat my people to meatball subs. Instead of cheese-filled meatballs for the subs, I created a variation on the theme last week and I am happy to report it was met with great approval: cheese-lined meatball subs.