Question: how do you heat up fully cooked meatballs?
Answer: The best way to reheat meatballs WITHOUT sauce. If you don't plan to serve the meatballs with sauce or gravy, reheat them in the oven at 300°F. Place the meatballs in a single layer on a baking sheet or in a baking dish, then cover them with foil to prevent drying, and heat until warmed through.