Add the butter and powdered/icing sugar to a large mixing bowl. Whisk together until light in color and fluffy. Either by hand or using an electric whisk.

Add the brandy in very small amounts while whisking. If you add it too fast it can curdle, separate or just turn into a smooth lump. If this happens, whisk in a little more powdered/icing sugar.

Chill until ready to serve over your warm dessert. I prefer to leave at room temperature so it is soft and spreadable. It will keep at room temperature for 1 to 2 days. Then it must be refrigerated and will keep in a sealed container for up to 1 month.