In the meantime, beat the eggs, sugar, calvados and salt until frothy. Mix in the cooled fat, baking powder and sifted flour.
Preheat the oven to 200 °.
Peel, quarter and core the apples. Cut into thin slices and fold 400 g of it into the dough.
Grease the springform pan and pour in the batter. Spread the remaining apple slices on the dough.
Place the cake in the preheated oven on the lower shelf and bake for 40-50 minutes at 200 °. Cover if necessary after 20 minutes of baking.
Take the cake out of the oven and carefully remove it from the mold. Place on a cake wire. Mix the powdered sugar and vanilla sugar and sprinkle the cake with it.