Fills and frosts two 8- 9-inch layers or frosts a 13x9-inch cake.
Note: To fill and frost three 8-inch layers, use 1/2 cup soft butter, 4 1/2 cups confectioners’ sugar, 2 teaspoons vanilla and about 3 tablespoons milk.
Source: Betty Crocker’s Cookbook - 1972, Page 125.