To make an easy marshmallow frosting, add 8 egg whites, 2 cups of sugar and 1/2 teaspoon of cream of tartar to a heat-proof mixing bowl. Place the bowl over a pot of simmering water, and whisk the mixture for three to four minutes, until the sugar is completely dissolved.
Remove the bowl from the heat. Using a mixer with a whisk attachment, whip the egg mixture on low speed. Gradually increase the speed to high, and beat the mixture for five to seven minutes until the egg whites form glossy, stiff peaks. Mix in 2 teaspoons of pure vanilla extract, and use the frosting immediately.
To make an easy marshmallow-buttercream frosting, add 1 cup of softened unsalted butter to a medium mixing bowl, and beat it at high speed until the butter becomes creamy.
Beat in one 7.5-ounce jar of marshmallow cream or fluff, then decrease the mixing speed to low. Mix in one cup of confectioners' sugar and 1/2 teaspoon of vanilla extract. Increase the speed to high, and beat the frosting until it is smooth and creamy.
To make a chocolate version of this recipe, mix in 1/2 cup of cocoa powder. This recipe makes enough frosting for one large layer cake or 24 cupcakes.