Mix flour and baking powder. Cream butter, 200 g sugar and vanillin sugar with the whisk of the hand mixer. Stir in eggs, milk and sour cream one after the other. Pour the dough into a greased, flour-dusted box form (approx. 30 cm long, 1 3/4 litre capacity) and smooth it down.
Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 1 hour. If necessary, cover with foil about 10 minutes before the end of the baking time.
Mix cream, 150 g sugar and grated coconut with a whisk and chill. Take the cake out of the tin, let it cool down for about 30 minutes, remove from the tin and let it cool down on a cake rack.
Roast the coconut chips in a pan without fat until golden brown. Cut the cake horizontally into 3 slices. Place the bottom cake layer on a cake plate and spread with about 1/3 of the coconut mixture. Place the middle cake layer on top and sprinkle with the coconut mixture.
Finish with the top shelf and spread with the remaining cream. Sprinkle with coconut chips.