Use this glaze to make our Toadstool Cupcakes. Make the glaze just before you are ready to ice the cooled cupcakes.
Melt butter in a saucepan over medium heat. Remove from heat. Stir in milk.
Whisk together butter mixture and the sugar in a large bowl until icing is opaque and thickened but still pourable, 4 to 5 minutes. Use immediately.