Grease a fat pan (approx. 32 x 39 cm; at least 3.5 cm deep) and dust with flour. Peel apples, quarter them, remove seeds, cut into slices and sprinkle with lemon juice
Pour cream into a mixing bowl. Wash and dry one cream cup, then use it as a "measuring cup
Add 1 cup (225 g) sugar, 1 vanilla sugar and lemon zest to the cream and beat until half stiff. Stir in the eggs one by one. Mix 3 cups (450 g) flour and baking powder, stir in briefly. Spread on the fat pan. Spread apples on top. Pre-bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 15 minutes
Meanwhile melt the fat at low heat. Mix 2 cups (300 g) flour, 3/4 cups (175 g) sugar, 1 vanillin sugar and 1 pinch of salt. Add fat in a thin stream, kneading everything with the dough hooks of the hand mixer to thick crumbles
Sprinkle 3 tablespoons of flour on the crumbles, grate the crumbles smaller between your fingers and sprinkle on the cake. Continue baking at the same temperature for about 20 minutes. Let it cool down