Cream fat, vanillin sugar, salt and sugar with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour and baking powder and stir in alternately with the milk. Divide the dough into three. Mix 1/3 dough and espresso powder. Mix 1/3 with cocoa powder. First fill the dark cocoa dough into a greased and floured box form (30 cm long, 2 3/4 litres capacity).
Carefully spread the espresso dough on top of it and the light-coloured dough on top. Bake the cake in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: level 2) for approx. 60 minutes (test with sticks). Remove the cake from the oven, let it cool down for approx. 15 minutes and turn out of the tin. Let it cool down on a cake rack. Mix the coffee and icing sugar to a thick icing and spread over the cake. Let the cake dry for about 30 minutes. Dust with cocoa before serving
waiting time approx. 1 1/2 hours