Preheat oven to 200*c and greasean 8 inch spring-form tin. Sift the flour into a bowl. In a separate bowl cream the butter and sugar, add eggs one at a time. Slowly stir flour and butter together. Beat in milk and vanilla until smooth . Pour into pan and bake for 20 minutes. Cool in pan for 10 minutes then let cool on rack.
For the icing, beat the butter and sift over icing sugar and cocoa. Beat until well combined. Add melted chocolate, you can add more or less depending on taste. Put in milk tablespoon at a time until the icing looks smooth, light and more like mousse. Beat until fluffy.
This icing can be spreaded on the cake with a pallet knife, though is also the perfect consistency to be piped on, this also looks fantastic and is great for birthday cakes.