Mix the egg white powder with the yoghurt and the egg in an ovenproof dish (e.g. a large cereal bowl) until smooth and season with cinnamon and stevia. Now cut the apple into small pieces and fold in together with the ground almonds.
Cook the whole thing in the microwave for 7 minutes at 480 W. Fall immediately after the Pling - Warning: very hot!
I ate it hot right away, but the cake tastes cold too.