Makes 250g/9oz (enough to cover the top of a 20cm/8" cake)
75g/3oz softened butter (I must stress that block butter is used here, it just isn't the same without it)
175g/6oz icing sugar, sieved
15-30ml/1-2 tbsp milk
1. Place butter in a bowl and beat until light and fluffy.
2. Add the sugar, and milk a little at a time, beating as you go until the sugar has gone and the mixture is light and smooth. If using food colouring, only add a little milk initially, adding more at the end, after you have added the colouring, if you need to.