First mix the natural yoghurt and the egg together in a soup bowl. Then add the protein powder, the baking cocoa and the baking powder and stir to a creamy, lump-free mixture. Finally, sweeten with stevia, honey or sugar as you like.
Place the soup cup on a plate (the cake could overflow) and bake in the microwave for about 3 minutes at 900 watts.
If you like, you can decorate the finished cup cake with fruits.