Peel and quarter the apples and remove the core. Cut quarter into cubes. Mix cubes with cinnamon.
Cream butter, sugar, salt and vanilla sugar with the whisk of the hand mixer. Stir in the eggs one after the other. Mix flour and baking powder and stir into the butter cream alternately with 75 ml milk.
Cut the dough in half. Stir cocoa and 3 tbsp. milk into one half. Pour light-coloured dough into a greased, floured fat pan of the oven (34 x 38 cm). Spread the dark dough over it.
Use a fork to swirl through the dough and smooth it down. Spread the apple cubes on the dough and bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 35 minutes.
Remove and let it cool down.
Heat the cream in a saucepan. Finely chop the chocolate coating and add it. Stir with a whisk until the chocolate coating is completely melted. Pour into a bowl and let it cool down. When the chocolate begins to set, spread everything on the cake and smooth it down.
Chill the cake for 1 1/2-2 hours.
Melt white chocolate over a warm water bath. Decorate the cake with it using a spoon, cut it into pieces and put it on a plate. Whipped cream is delicious with it.