Whisk the egg, vanilla & maple syrup together in a large mug, or small ramekin.
Add the dry ingredients and beat with a spoon until all ingredients are mixed well. Add the yoghurt and stir again until you have a smooth, thick batter.
Cook in the microwave for 2-2½ minutes, at 50 or 75% power. The bottom should still be soft, or even a little bit gooey, depending on the consistency you prefer.
Use a knife to loosen the cake from the sides of the mug, then turn it out upside down into a bowl. Enjoy as is, or top with fresh berries and a dollop of Greek yoghurt.
Notes
Serve with fresh berries and cream for dessert, or with Greek yoghurt for a delicious indulgent breakfast.
Use unflavoured protein powder instead of oat flour for a higher protein cake.