Sift together flour, soda, salt, cocoa. Work with a spoon until light ½ cup shortening. Gradually add, blending well, 1cup sugar, add 1 egg. Beat well, add the dry ingredients with 1 cup milk and 1 tsp vanilla. Blend well after each addition. Drop by tsp on a cookie sheet. Bake in oven 350 for 10 minutes.
Filling: Put 2 c confectioners sugar, ¾ c shortening, 2 egg whites, ½ teaspoon salt, 1 teaspoon vanilla into a large bowl and beat until thick and creamy. Spread filling between two whoopie pies.