Sift the confectioners’ sugar into a medium bowl.
Add the whole milk and melted butter and whisk until smooth.
If the icing is too thick, whisk in additional whole milk 1 teaspoon at a time until thinner.
If desired, whisk in food coloring.
Dip cookies into icing or use a spoon to spread it into a thin layer on tops of cookies.
Let the cookies sit at room temperature until the icing sets, about 10 minutes.
