You are here: Home » Recipes » Marshmallow Whoopie Pie Filling Marshmallow Whoopie Pie Filling Recipe by Hanover Inn Yield PrintEmail Ingredients 1 cup butter, softened1 cup powdered sugar1 1/3 cups marshmallow fluff1/4 teaspoon salt1 1/2 teaspoons vanilla extract Instructions Cream together the butter and sugar until light and fluffy. Add the marshmallow and beat until well combined. Add the salt and vanilla. Spread or pipe filling onto one side of the whoopie pie and top with another to assemble the whoopie pies. For Mint Marshmallow Filling: Add ¼ cup crème de menthe liquor at the end of mixing For Champagne Filling: Add ¼ cup crème de menthe liquor at the end of Recipe courtesy of the Hanover Inn, Hanover, N.H.