Mix the sugar, orange sugar and butter / margarine until soft. Gradually stir in the eggs and egg yolks, beat everything until frothy. Stir in cocoa powder. Add flour and baking powder, add 1 to 2 tablespoons of milk, mix well. Spread the dough in a greased springform pan (26 cm) and cover with the mandarins.
Beat the 2 egg whites until stiff. Mix the sour cream, sugar, orange sugar and desiccated coconut, fold in the egg whites, distribute everything nicely on the cake.
Bake at 160 ° convection for approx. 50 minutes, cover a little at the end if necessary.
Dust with powdered sugar or serve just like that.
Tips: the amount of cocoa can be increased and those who like coconut can also add 3 tablespoon desiccated coconut to the topping.