King Arthur Flour's Perfect Buttercream Frosting

This rich, creamy frosting is lovely swirled atop a cake or cupcakes.
3/4 cup (5 1/4 ounces) granulated sugar
1/4 teaspoon salt (ONLY if you use unsalted butter)
1/2 cup (4 ounces) boiling water
1/4 cup (1 ounce) meringue powder
1 tablespoon (1/2 ounce) vanilla extract
4 cups (16 ounces) sifted confectioners’ or glazing sugar
2 cups (4 sticks, 16 ounces) soft butter, vegetable shortening, or a combination of both*

*We love the flavor of butter, but if your cake will be sitting in a hot place, using some (or all) vegetable shortening will help keep the frosting from melting.Earth Balance sticks work well for me- if dairy is not an issue I do half butter, half EB.

Dissolve the sugar (and salt, if you’re using it) in the boiling water, and cool to room temperature. Mix in the meringue powder. Use a mixer to beat on slow speed for several minutes, until the powder is dissolved and the mixture is foamy. Increase the speed and beat until soft peaks form. Beat in the vanilla, then the confectioners’ or glazing sugar. Add the soft butter a few tablespoons at a time, beating well after each addition.
Yield: Enough frosting to fill and frost an 8" layer cake or 24 cupcakes.

VARIATIONS: For coconut frosting, add 4 to 5 drops coconut flavor and 1/4 cup (1 ounce) coconut milk powder along with the confectioners’ sugar. Or flavor to taste with almond extract; coffee flavor; 2 teaspoons espresso powder dissolved in the boiling water; butter-rum flavor, or 2 tablespoons fruit purée, added after the confectioners’ sugar. Be aware that adding fruit or espresso will change the color of the frosting.