You can, indeed! Frozen cakes may thaw with a slightly different texture than a fresh-baked cake, especially if it's decorated. But if you wrap the cake in an air-tight container or cut and store slices in an air-tight bag, the cake freezes well for a couple of months. For the best freezing, use the water displacement method described below. To create an airtight seal using water displacement, put the cake in a large zipper food storage bag and fill a large mixing bowl with water. With the bag unsealed, gently push the bottom into the water. Continue submerging the bag and stop when the water is just below the seal. Seal the bag closed while it's submerged, then remove it and dry the outside. You should notice the bag clings to the contents (cake) in a similar way to an item that was vacuum-sealed.