This is a recipe for a fluffy chiffon cake that can be made in just 90 seconds in the microwave using rice flour and Calpis. Simply mix eggs, oil, water, Calpis concentrate, rice flour, and baking powder in a mug and heat in the microwave to create a moist cake with a slightly sweet and sour taste, packed with lactic acid bacteria. It's easy to make, so it's recommended for beginners.