Food & Cooking Recipes Dessert & Treats Recipes Whoopie Pie Filling 3.2 (283) 25 Reviews 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 September 28, 2016 Print Rate It Share Share Tweet Pin Email Yield: Makes 3 3/4 cups This delicious whoopie pie filling is courtesy of Cranberry Island Kitchens. Ingredients 1 cup (2 sticks) unsalted butter, preferably organic, room temperature 2 cups sifted confectioners' sugar 1 jar (7 ½ ounces) marshmallow Fluff 2 teaspoons pure vanilla extract, preferably organic Directions In the bowl of an electric mixer fitted with the paddle attachment, cream together butter and sugar until pale and fluffy, about 3 minutes. Add Fluff and vanilla and continue mixing until well combined. Rate it Print