For the royal icing: In the bowl of a stand mixer fitted with a paddle attachment, combine the powdered sugar, egg whites, and lemon juice. Beat on low speed until combined, then increase to ...
Note: If you are icing a 3-layer cake, use the following recipe proportions: 1 1/2 cup unsalted butter, 8-10 confectioners' sugar, 3/4 cup milk, and 1 tablespoon vanilla extract. Recipe from More ...
To make doughnut icing, just combine confectioners' sugar and water with whatever flavor you want. The icing can harden pretty fast, so make sure you work quickly. If it hardens, the sprinkles won ...