Method
Make up the black coffee. While it is still hot, add the chocolate powder and stir together.
In a large mixing bowl cream the butter and sugar together. Add the beaten egg, one at a time, together with a tablespoon of the flour and beat until well mixed.
Sift the flour and bicarbonate of soda. Fold some of the flour and bicarb into the cake mixture, then some of the yogurt. Alternate folding in the flour and yoghurt until it is all evenly mixed in.
Spoon into the cake tins and bake at 170 deg C (150 deg C for fan ovens), Gas Mark 4, for 25 minutes, until the cake is firm to the touch.
Turn out and allow to completely cool, before decorating with the chocolate frosting.
