In a saucepan melt butter.

Stir in brown sugar and bring to a boil.

Reduce heat to medium and continue to stir for two minutes.

Add the milk and return to boil (continually stirring).

Reduce heat to a simmer.

Gradually stir in powdered sugar and beat until smooth. Add more powdered sugar if needed or warm water if the consistency is too thick.

Drizzle or spoon onto cookies while mixture is still warm.