Dessert & Treats Recipes Cake Recipes Fillings & Frostings Buttercream Frosting Recipes Brown-Sugar Buttercream Frosting 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: 2 cups Ingredients 2 large egg whites ½ cup packed light-brown sugar ¾ cup (1 ½ sticks) cold unsalted butter, cut into tablespoons Directions Put egg whites and sugar into the heatproof bowl of an electric mixer set over a pan of simmering water. Cook, whisking constantly, until sugar has dissolved and mixture is warm to the touch (about 160 degrees). Attach the bowl to the mixer fitted with the whisk attachment. Beat on high speed until stiff (but not dry) peaks form. Continue beating until mixture is fluffy and cooled, about 6 minutes. Switch to the paddle attachment. With mixer on medium-low speed, add butter, several tablespoons at a time, mixing well after each addition. (If the frosting appears to separate after all the butter has been added, beat on medium-high speed until smooth again, 3 to 5 minutes more.) Reduce speed to low; mix to eliminate any air bubbles, about 2 minutes. Stir with a rubber spatula until frosting is smooth. Rate it Print