Butter Cream
2oz unsalted butter
4oz icing sugar, sifted
1 tablespoon milk
Beat the butter with half the icing sugar until smooth. Add the remaining icing sugar with the milk and any flavouring. Beat until creamy.
This quantity is enough to fill (quite adequately) an 8 inch sandwich cake. If stored in an airtight container, this butter cream can be kept in the fridge for several weeks.