For the blackberry chocolate cake, first separate the eggs. Beat the egg whites with a pinch of salt until stiff. Mix egg yolks, powdered sugar and vanilla sugar until foamy.
Add oil, drinking chocolate powder, rum and spices – mix again briefly. Mix in flour. Carefully fold in beaten egg whites. Pour into a greased and floured baking pan, spread blackberries on top and bake at approx. 170 °C.