Bundt cakes (whole or sliced) freeze very well. If you have leftover slices that you want to freeze individually, store them in zip-top bags or wrapped in plastic wrap. When you want to enjoy a slice, thaw at room temperature for a few hours or in the refrigerator overnight. If you are freezing the entire Bundt, just make sure that it has completely cooled before you wrap it tightly and place it in the freezer. Thaw whole Bundts overnight at room temperature or in the refrigerator.