Best Buttercream Frosting 4 Reviews By Anonymous recipe Comments | 0 Favorites | 260 Print Best buttercream frosting–great for Aunt Mary’s Chocolate Cake! Best Buttercream Frosting Ingredients 1 cup butter, softened1 cup white sugar4 tablespoons all-purpose flour1 cup milk1 teaspoon vanilla extract Instructions 1 In small saucepan cook flour and milk until it forms a ball, stirring constantly. Cool to room temperature. 2 With an electric mixer, beat butter and sugar until fluffy. 3 Beat both mixtures together on high speed until fluffy and smooth. Add vanilla and beat until combined. Refrigerate for about 1/2 hour, until it is of spreading consistency.