(serves 12, if you make big whoopie pies.) (Trying so hard not to make a "Make Big Whoopie" joke.)
4 cups flour
1 cup cocoa (preferably Dutch processed)
2 tsp. baking soda
1 tsp. salt
2 cups packed brown sugar
2 sticks butter, softened but still cool
2 large eggs, room temp
2 tsp. vanilla
2 cups buttermilk
3 sticks butter, softened but still cool
2 1/2 cups powdered sugar
3 tsp. vanilla
1/4 tsp. salt
5 cups marshmallow creme
Directions: Heat oven to 350 degrees. In a large bowl, cream together the butter and sugar with a hand mixer...about 4 minutes. Add the egg and vanilla.
In a separate bowl, mix together the dry ingredients: flour, cocoa, baking soda, and salt. Pour some of it into the butter/sugar mixture, alternating with the buttermilk. Drop the batter onto sheet pans covered in parchment paper or with a silpat. Give the cookies plenty of room to spread. You may want to flatten them slightly so you don't end up with "whoopie balls".
Bake for about 7 minutes, rotate the pan in the oven and bake for 7 minutes more OR until the cookies "spring bag" when lightly pressed with your finger.
For the filling, beat the softened butter and sugar until fluffy. Add the vanilla and salt. Beat in the marshmallow creme. Mix well. Refrigerate for about 30 minutes. Dollop on a cookie, take another cookie on top and press together until the filling spreads to the edges. Eat!
Try to match up the cookies for size so you have less "leakage" of the filling around the edges. Using a cookie scoop will help you get equal portions.