Follow the full recipe, then let the meatballs cool completely. Place the cooled meatballs on a lined baking sheet and freeze for 1-2 hours. Then place in a freezer bag and store for up to 3 months! To reheat simply pop them directly in the oven or the air fryer and cook at the listed temperatures until they are hot throughout. (About 12-15 minutes in the air fryer or 35-45 minutes in the oven.)