In a mixing bowl, with the paddle attachment, cream shortening and sugar until light and fluffy.
1 c. Crisco shortening, 2 c. sugar
Add the eggs and mix well.
2 large eggs
Add the buttermilk and vanilla. Mix again.
1 c. buttermilk, 2 tsp. vanilla extract
Add the flour, sifted cocoa powder, and salt. Mix only to combine.
4 c. all-purpose flour, 1 c. cocoa powder (sifted), 1 1/2 tsp. salt
Add the baking soda to the hot water and stir to dissolve. Slowly mix this into the batter until combined.
1 c. hot water, 2 tsp. baking soda
Drop by cookie scoop or spoonfuls onto a greased baking tray.
Bake for about 9 - 10 minutes at 350°. (When finished, cookies will spring back when lightly touched.)
Remove to a wire rack to cool.
Whoopie Filling:
With the whisk attachment, beat egg whites until foamy.
3 large egg whites
Add the remaining ingredients and mix.
1 c. Crisco shortening or softened butter, 4 c. powdered sugar, 4 Tbsp. all-purpose flour, 2 Tbsp. milk, 1 Tbsp. vanilla extract, 1/8 tsp. salt
Whip on high speed until the filling is light and fluffy.
To make Whoopie Pies:
Pair the cooled cookies and spread the filling between the two cookies.
Wrap each individual whoopie pie in plastic wrap.
Whoopie pies that won't be eaten within the first few days can be stored in an airtight container in the freezer to keep them fresh. Remove from the freezer to thaw at least a half-hour before serving.
Notes
If you don't have buttermilk you can make your own by adding 2 Tbsp. of lemon juice to a cup and fill it with whole or 2% milk. Let it sit for several minutes until thickened.You can make these whoopie pies into any size you want. This recipe makes about 40 small whoopie pies but only about 10 giant whoopie pies.If you don't feel comfortable with consuming raw egg whites, you can use a basic buttercream frosting to fill them.I used my 1" cookie scoop to bake mini whoopie pies and filled the same cookie scoop heaping full to pile the filling onto my cookies.