Cream the room-warm butter with birch sugar. Add the eggs little by little.
This is followed by the lemon peel and milk.
Mix flour and baking powder in a bowl and slowly fold both into the batter.
Pour the batter into a greased baking pan.
Your cake needs about 30 minutes. In the meantime, prepare the meringue cream.
Grate the apple with a grater. Mix in the cinnamon.
Beat the egg whites with birch sugar until stiff.
When your cake comes out of the oven, spread the apple-cinnamon mixture on top. Finally, spread the foamy egg whites over the apples.
Now put your apple pie with meringue topping in the oven for a few minutes at 200 degrees. It's best to stick directly to the apple pie - the meringue cream can darken very quickly.
And you're done :) If you like, you can spread a few pieces of apple on the meringue. Important: Rub with lemon beforehand, otherwise they will quickly turn brown.