Cream together butter and 1 cup sugar, add egg. Sift together 2 cups flour, cocoa, soda, 1/2 teaspoon salt and baking powder. Add vanilla and milk.
Step 2
Drop by tablespoon full onto ungreased cookie sheet and bake 7-8 minutes at 425 degrees F (220 degrees C). Cool completely and make sandwiches using following filling.
Step 3
To Make Filling: Combine 2 1/2 tablespoons flour and 1/2 cup milk and cook until it turns to thick paste. Cool completely.
Step 4
Cream together the 1/2 cup sugar, 1/4 teaspoon salt, 1/2 cup shortening, and 1/2 teaspoon vanilla. Add cooled paste and beat until fluffy. (This will take awhile and if your paste is not completely cooled it will look curdled. ) I usually double this recipe for the filling.