In a large bowl, stir together confectioners’ sugar, milk, melted butter, vanilla, and salt until smooth. Divide glaze among 3 bowls (about ½ cup [146 grams] each). Tint one bowl with red food coloring, tint one bowl with blue food coloring, and leave remaining bowl plain. Use immediately.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/patriotic-sprinkle-cake/