Start the oven at 200 degrees Celsius.
Peel the apples and cut the seeds. Cut in slices
Whip the butter and the sugar fluffy with an electrical mixer.
Add egg one by one while still whipping.
Add the flour, milk and baking powder bite by bit while still whipping.
Cover a baking form 35x 25 centimeters with a baking paper.
Pour evenly the batter in the baking form.
Place evenly the apple slices over the batter.
Sprinkle evenly the cinnamon and sugar over the cake.
Place in the lower part of the oven for 30 minutes.
Take out the cake and let it cool down in room temperature.
Cut the cake in smaller squares before serving it.