500g icing sugar
3 large egg whites
1 teaspoon glycerine (or honey)
Place the egg whites in a bowl, and before you whisk, stir in the icing sugar, a bit at a time, until the icing is thick and falls from the spoon. At this point, stop adding any more sugar and whisk with an electric whisk for 10 minutes or until the icing stands up in stiff peaks, then stir in the glycerine or honey. Leave under a damp cloth.