This recipe uses just two ingredients—cider and gelatin—to make a clear cake in a paper cup. It's adorable, has a wobbly texture, and a pleasant sweetness, making it a hit with children. While it doesn't retain the fizz of carbonation, its ease of preparation makes it perfect for a home café or dessert. The key to a delicious result is to thoroughly soak and dissolve the gelatin, then mix it in while the cider is still warm.