Beat the butter with the sugar until light and fluffy. Gradually beat in the eggs. Sieve together the flour, cocoa powder and baking powder and fold into the mixture along with the milk. Line a muffin tin with about eight paper cases and divide the mixture evenly between them. Bake in an oven preheated to 180ºC for about 15 mins. To make the chocolate icing, melt the chocolate and butter, remove from the heat and beat in the sugar and water.
Allow the cakes to cool and then ice with chocolate icing and decorate with chocolate buttons.