You can freeze leftover pieces of cake from special occasions to save them for dessert or packable lunch snacks in the future. Ordinarily, cake eaters freeze cakes as a whole, either frosted or unfrosted. However, you can freeze individual pieces as long as you tightly wrap each piece to prevent freezer burn. CakeBaker recommends unwrapping the cake pieces before thawing completely to avoid pieces of the packing from remaining stuck to the cake.
Lay out one piece of plastic wrap on a flat surface. Place the piece of cake on the cling wrap. Fold the cling wrap all the way around the cake piece, making sure all the edges are covered.
Spread out a sheet of foil. Place the wrapped cake piece on the foil. Wrap the foil around the cake as you did with the plastic wrap.
Slide the wrapped cake piece into a plastic freezer bag. Seal the bag, squeezing out as much air as possible before putting it in the freezer.