Mix butter, sugar and vanilla sugar with the whisk of the hand mixer for about 8 minutes until creamy. Stir in the eggs one after the other. Stir in almonds. Mix flour and baking powder, add with milk and stir briefly.
Put the dough into a greased springform pan (22 cm Ø) sprinkled with almonds and smooth it down. Wash apples, quarter them, remove seeds and cut them into slices. Place apples fan-shaped on the dough.
Bake in the preheated oven, 2nd shelf from below (electric oven: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 45 minutes.
Cover with aluminium foil approx. 10 minutes before the end of the baking time if necessary. Leave the finished cake to cool in the mould on a cake rack. Dust with icing sugar. Whipped cream is delicious with it.