Dessert & Treats Recipes Cake Recipes Fillings & Frostings Buttercream Frosting Recipes Swiss Meringue Buttercream for Sprinkle Cake Be the first to rate & review! By Martha Stewart Test Kitchen Martha Stewart Test Kitchen The recipes developed by our test kitchen team have undergone a rigorous process of development and testing, ensuring that every element is optimal, from ingredient amounts to method and cooking time. This process includes triple-testing recipes to ensure they meet our high standards. The many stellar cooks and food editors who have been part of our team include Sarah Carey, Lucinda Scala Quinn, Jennifer Aaronson, Shira Bocar, Anna Kovel, Greg Lofts, Riley Wofford, Lauren Tyrell, and Lindsay Leopold. Editorial Guidelines Updated on May 16, 2017 Print Rate It Share Share Tweet Pin Email Yield: Makes 6 1/2 cups This fluffy frosting is the perfect canvas for the Sprinkle Cake's rainbow of tiny candies. Ingredients 6 large egg whites 1 ⅓ cups sugar Pinch of salt 1 pound plus 6 tablespoons (4 ¾ sticks) unsalted butter, cut into tablespoons, room temperature 1 ¾ teaspoons pure vanilla extract Directions Combine egg whites, sugar, and salt in the heatproof bowl of a standing mixer set over a pan of simmering water. Whisk constantly by hand until mixture is warm to the touch and sugar has dissolved (the mixture should feel completely smooth when rubbed between your fingertips). Attach the bowl to the mixer fitted with the whisk attachment. Starting on low and gradually increasing to medium-high speed, whisk until stiff (but not dry) peaks form. Continue mixing until the mixture is fluffy and glossy, and completely cool (test by touching the bottom of the bowl), about 10 minutes. With mixer on medium-low speed, add the butter a few tablespoons at a time, mixing well after each addition. Once all butter has been added, whisk in vanilla. Switch to the paddle attachment, and continue beating on low speed until all air bubbles are eliminated, about 2 minutes. Scrape down sides of bowl with a flexible spatula, and continue beating until the frosting is completely smooth. Keep buttercream at room temperature if using the same day. Rate it Print