Place the butter in a saucepan over medium-high heat. Cook stirring constantly until the butter is a nice tan colour. If it gets dark brown or black you have allowed it to burn too long. When butter has been "burned" remove the saucepan from the heat.
Slowly mix in icing sugar and vanilla. Beat on high speed of an electric mixer until light and fluffy.
Beat in the milk a tablespoon at a time until desired spreading consistency is achieved.
Use icing immediately as this icing will set up quickly.