A cake recipe for all foodies:
Beat butter with oil, sugar and venilla sugar until creamy. Add eggs one at a time, beating each egg for at least a minute. Mix flour, cornstarch (maize starch) and baking powder, sift and stir lemon zest into the batter. Drain wild blueberries on top, reserving juice. Melt one bar of chocolate, stir until smooth, add a heaping tablespoon of sour cream or crème fraiche and stir well. Pour the remaining sour cream or crème fraiche into a large enough bowl and add the chocolate mixed with the sour cream or crème fraiche. Add the blueberries to the sour cream and prepare the whole thing with a blender. Spread 3/4 of the dough on a prepared baking tray with a higher edge, greased or possibly lined with parchment paper. Spread the sour cream evenly on the dough and turn a beater of the hand mixer through the dough, so that a little of the sour cream is stirred into the dough. Mix the remaining batter with milk and cover the remaining sour cream with it. Bake in a heated oven at 180 °C for about 30 minutes. Break a bar of Milka into pieces, melt in a water bath, stir until smooth. Stir the sifted powdered sugar with a little blueberry juice so that it can be stirred smooth. Stir the melted chocolate into the powdered sugar icing by the teaspoonful. Spread the icing on the cooled sheet cake and let it set. Fill the third Milka bar with