These sandwich cookies consist of a pair of chocolate wafers filled with rich vanilla buttercream and iced with chocolate butter frosting.
For cookies, beat shortening with an electric mixer on medium to high speed for 30 seconds. Add about 1 cup of the flour, half the buttermilk, the sugar, 2/3 cup cocoa, egg, baking soda, 1 teaspoon vanilla, and 1/8 teaspoon salt. Beat until thoroughly combined. Beat in the remaining 1 cup flour and remaining buttermilk. Drop by rounded tablespoons 2 inches apart onto ungreased cookie sheets. Bake in a 350 degree F oven for 8 to 10 minutes or until the edges are firm; cool on a wire rack.
For filling, in a saucepan combine 3/4 cup milk and the 1/4 cup flour. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. Remove from heat; cool.
In a mixing bowl beat 3/4 cup margarine or butter with an electric mixer on medium to high speed for 30 seconds. Add the 2 cups powdered sugar; beat until fluffy. Add 1 teaspoon vanilla. Beat cooled milk mixture, 1 large spoonful at a time, into margarine mixture. Beat on high for 1 minute or until filling is smooth and fluffy. Spread about 2 tablespoons filling on the flat side of half the cooled cookies. Top with the remaining cookies; flat side down.
For frosting beat together 1/4 cup cocoa powder and 3 tablespoons butter or margarine. Gradually beat in 1 cup of the powdered sugar. Slowly beat in 2 tablespoons milk and 1/2 teaspoon vanilla. Gradually beat in remaining 1 cup powdered sugar. Beat in additional milk, if needed, to reach spreading consistency. Frost cookies. Store in the refrigerator. Makes 14 filled cookies.