Chocolate Buttercream Icing

It's not a great picture, but this is my homemade Chocolate Buttercream Icing. It's an old recipe, but a goof proof one, which is good for me!!! It seems like a recipe gone bad after adding all the sugar. The icing is very dry, but after adding the milk, it whips right up into the perfect spreading consistency! 

½ cup solid vegetable shortening

½ cup (1stick) butter, softened

¾ cup cocoa

1 teaspoon vanilla extract

4 cups sifted confectioners' sugar (Powdered Sugar)

3-4 tablespoons milk

In large bowl, cream shortening and butter with electric mixer. Add cocoa and vanilla. Gradually add powdered sugar, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar has been mixed in, icing will appear dry. Add milk and beat at medium speed until light and fluffy. Keep bowl covered with a damp cloth until ready to use.