Make Ahead and Freeze: For best results, freeze the meatballs individually. Allow the meatballs to cool slightly, and then arrange them in a single layer on a baking sheet lined with parchment paper, leaving some space between. Freeze for 2 hours, and then transfer to a freezer-safe container (I use a gallon-size Ziploc bag). Next time you need a quick, delicious meal, pull out as many as you need, place them on a foil-lined baking sheet, and reheat in the oven for 15 minutes at 375°F. Frozen meatballs should be enjoyed within 2-3 months.