Mix the soft butter with the yolk and sugar until creamy. Stir in the flour, pudding powder, nuts, cocoa and the cream mixed with baking powder, grate the peeled apples over it and fold in with the egg whites.
Spread the dough on a prepared 40 sheet and bake in a preheated oven at 160 ° for about 20-25 minutes.
When cold, cut the cake in half and spread jam on one half, place the second half of the cake on top and coat with chocolate icing.