Using a fork whisk together the egg, applesauce, and almond butter in a mug that holds at least 12 oz (375 ml). Stir in the flour, infant cereal, baking powder, and cinnamon.
Microwave for 60-90 seconds. It’s done when a toothpick inserted into the centre comes out clean. CAUTION - mug may be hot! Remove the cake from the mug and allow it to cool to a safe temperature before slicing and serving to your baby.