Dessert & Treats Recipes Cake Recipes Fillings & Frostings Buttercream Frosting Recipes Swiss Meringue Buttercream for March Cupcakes 3.4 (5) 1 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 March 19, 2018 Print Rate It Share Share Tweet Pin Email Yield: 4 cups Ingredients 5 large egg whites 1 ¼ cups sugar 2 cups (4 sticks) unsalted butter, room temperature 1 teaspoon vanilla extract ¼ teaspoon coarse salt Directions Combine egg whites, and sugar in the heatproof bowl of an electric mixer. Set bowl over a pan of simmering water. Whisk constantly until sugar has dissolved and whites are hot to the touch, 5 to 7 minutes. Transfer bowl to the electric mixer. Using the whisk attachment, mix on low speed, gradually increasing to high speed, until stiff, glossy peaks form, about 10 minutes. At low speed, add butter to egg whites, and beat until smooth. Add vanilla and salt, and continue mixing until incorporated. Rate it Print