CAKE MIX: Preheat oven to 180ºC.

Mix cocoa powder and hot water until smooth and set aside to cool.

Cream the butter and sugar and add the eggs one at a time until mixture looks creamy.

Add the cocoa powder mixture and the plain yoghurt the sugar mixture.

Sift together all remaining dry ingredients (flour, bicarb, salt and baking powder) and slowly add to the other mixture.

Pour the finished mixture into a greased cake tin and bake in the oven for about an hour. Wait for cake to cool before removing from tin.

ICING: Place all ingredients in a heavy-based saucepan and melt over a low heat. Ensure that the cake is cool before icing.