Place the sugar and vanilla sugar in a bowl and whisk the eggs.
Mix the baking powder with the flour and gradually add it to the eggs. Continue stirring. Then add the melted butter and mix.
Peel and dice the apples. Grease the baking dish and add the apples (sprinkle with sugar or cinnamon if desired). Now pour the batter over the apples and smooth the surface.
Place in a preheated oven at 180°C and bake for 30–45 minutes (baking time may vary; test with a toothpick before removing the cake from the oven). Sprinkle the finished cake with powdered sugar.
