I hadn't copied far enough to get the frosting. Here it is:
Browned-Butter Frosting
1/2 cup butter
2 cups powdered sugar
1 1/2 teaspoons vanilla
3 tablespoons milk
Heat butter in saucepan over medium heat past the melting point until it boils and turns a delicate brown.
Remove from the heat and immediately whisk in the remaining ingredients. This should make a thick glaze. Using a spatula, smooth over the top of the Monkey Bars immediately. Work quickly, it hardens fast!