Chop the chocolate and melt over a warm water bath. Dissolve coffee in 4 tablespoons of hot water. Cream fat, sugar and salt with the whisk of the hand mixer. Stir in eggs one after the other. Mix flour and baking powder, stir alternately with 1/4 litre milk into the fat egg mass.
Divide the dough into three. Stir chocolate and half coffee into one third. Stir the remaining coffee into the second third. Stir 2 tablespoons of milk into the third third. Pour the dough alternately into the greased fat pan of the oven (32 x 39 cm). Use a fork to spiral through the dough and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 40 minutes. Remove and let cool off. Cut cake into squares.
Pour the dough alternately into the greased fat pan of the oven (32 x 39 cm). Use a fork to spiral through the dough and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 40 minutes. Remove and let cool off. Cut cake into squares. Decorate cake pieces with cream, crushed coffee beans and cocoa sugar