2 large (US extra-large) egg whites
2 tsp liquid glycerine
450g/1lb/3⅓ cups icing (confectioner’s) sugar, sifted
1 Put the egg whites and glycerine in a bowl and stir just enough to break up the egg whites. Add a little of the sugar and mix gently with a wooden spoon to incorporate as little air as possible.
2 Add a little more sugar as the mixture gets lighter. Keep adding the sugar, stirring gently but thoroughly, until the mixture is stiff and stands in soft peaks.
3 Transfer to an airtight container, cover the surface with clingfilm (plastic wrap) to prevent it drying out, then seal. When required, stir the icing slowly.
4 This is enough to cover the top and sides of a 20cm/8in cake.