Cream the shortening and brown sugar together.
Add the eggs.
In a separate bowl, mix the flour, cocoa, baking soda, and salt.
Alternate folding the dry ingredients and the buttermilk into the creamed mixture.
Scoop the batter onto a baking sheet and bake for about 9 minutes.
For the filling, cream the shortening, vanilla, and water together.
Gradually add the powdered sugar and mix until smooth.
Assemble the whoopie pies by placing the filling between two cake-like cookies.
