Steps:

• Preheat oven to 325 degrees F (165 degrees C).
• Mix the flour, 2 cups of the sugar, baking soda, 6 tablespoons of the cocoa, salt, vegetable oil, vinegar, 2 teaspoons vanilla, and the water together. Stir until just combined. Pour batter into on ungreased 13x9 inch baking pan.
• Bake at 325 degrees F (165 degrees C) for 30 to 35 minutes. Let cake cool than ice.
• To Make Icing: Beat together the butter or margarine, vegetable shortening, 1 cup sugar, milk, and 1 teaspoon vanilla. Continue beating for 10 minutes. Spread over cooled cake.

Steps:

• Preheat oven to 450 degree F. Coat cookie sheets with cooking spray. I like to line my sheets with parchment paper, but it isn't necessary. It helps save time with clean up. NOTE: I doubled the recipe when posting this. Just and fyi as you browse throught the photos and notice 4 eggs, etc.
• Start by prepping the first step of icing. In a saucepan, add milk and flour. Heat on low heat. Stir constantly until mixture becomes pasty. Cooking time takes approximately 10 minutes. You must stir constantly as it cooks to prevent mixture from becoming lumpy. When done, remove from heat & transfer to a bowl. Put in refrigerator to cool completely while you prep the cake tops and bottoms, about one hour. Do not cover, or if you must, cover lightly to prevent condensation from forming. We will finish the icing last.
• You will need 3 mixing bowls to make cake mixture. In first bowl, combine sugar, Crisco, & eggs. Cream together.
• In the second bowl, combine Sour Milk, Boiling water, salt, cocoa, and vanilla. Mix well until cocoa is dissolved completely into liquid. (To make sour milk, add 1 teaspoon lemon juice or white vinegar to 1 Cup of milk, stir and allow to sit for a few minutes.)
• In the third bowl combine flour, baking powder, and baking soda, mix well.
• Next, add the cocoa liquid mixture to sugar cream and mix well on low speed of mixer. gradually add flour mixture. Mix batter until all is blended well.
• Drop batter onto cookie sheets, approximately 1/8 of a cup. I use a cookie scoop or small cupcake batter scoop. Bake in preheated oven for 5-7 minutes. Toothpick inserted in middle of cake will come out clean when done. Remove from cookie sheet & place on cooling rack, allow to cool completely.
• Complete icing: In mixer, add Crisco, soft butter, vanilla & salt. Cream together. Add flour/milk mixture, & mix on low speed, gradually add powdered sugar until well blended. Place in refrigerator for about 20 minutes.
• Put together your Whoopie Pie! I like to use a pastry bag, and pipe my icing onto one cake, flat side, then top with another. It saves time and a big mess! Refrigerate for approximately one hour before serving. Keep refrigerated or in freezer. Makes an awesome midnight snack! :)