Heat butter in a saucepan over medium heat, until it is boiling and a delicate brown.
Remove from heat and add the remaining ingredients.
Add milk or half & half to get to the correct consistency; the frosting should be thicker than a glaze and thinner than frosting.
Using a spatula smooth over the top of the Monkey Squares immediately.
Chef's notes: The frosting will be easier to spread once it is on the warm Monkey Squares.