250g unsalted butter
500g icing sugar
Vanilla extract
Milk
Cream the room temperature butter in a stand mixer for about 5 minutes until its really pale and soft, add in a dash of vanilla extract, add the icing sugar bit by bit adding in some room temperature whole milk if needed which it usually is, usually a couple of tablespoons depending on quantity. Then I leave it for another few minutes until its really fluffy. The longer I leave it mixing the fluffier it gets and is much easier to eat without being too dense and sickly.