One the cupcakes are cooling on the tray start preparing your icing. Put the milk, butter and sugar in a saucepan over a high heat. Stir constantly as you bring it to a boil, when its boiling stop stiring and leave it for 1 minute. After the minute of boiling take the saucepan off the heat and add half of the sieved icing sugar stiring well untill combined. Leave to cool a little ( a few minutes) then add the rest of the icing sugar stirring untill completly combined. Ice the cakes immediatly as the icing set quickly, keep stiring the icing so as not to let it set. ( the icing will keep up to a week in the fridge, just add a little milk when you go to reheat it in the microwave). If you wish to decorate the cupcakes futher, ( I sometimes use dried banana slices) do it immediatly as the icing sets in minutes.