Mix the margarine with the sugar until frothy. Mix in the eggs one by one. Sift the flour with baking powder over it and stir in briefly. Spread the batter on a baking sheet lined with baking paper and cover with the sliced apples. Bake in the preheated oven at 175 ° C on the middle rack for about 30 minutes.
Whip the cream with the vanilla sugar and cream stiffener until stiff, fold in the sour cream. Spread on the cooled cake and sprinkle with cinnamon and sugar (mix beforehand).
Be sure to let it steep for a day and keep it cool