Whoopie Pie

1/2 cup butter (room temperature)
1 cup firmly packed brown sugar
1 egg (room temperature)
2 cups cake flour
1/2 cup Ghiardelli unsweetened cocoa
1 tsp baking powder
1 tsp baking soda
1 tsp salt
2 tsp Nielsen-Massey Vanilla bean paste (or pure vanilla extract)
1 cup buttermilk (room temperature)
2 sticks butter
1 1/2 cup Marshmallow Fluff
2-3 cups of confectioners sugar (depending on consistency)
2 tsp vanilla bean paste (or vanilla extract)
Preheat oven to 350 degrees F. Lightly grease baking sheets (you can also use parchment paper to transfer cakes on and off of cookie tray)
In a large bowl, cream together butter, brown sugar, and egg. In another bowl, combine cocoa, flour, baking powder, baking soda, and salt.

In a small bowl, stir the vanilla extract into the buttermilk. Add the dry ingredients to the butter mixture, alternating with the buttermilk and beat until smooth.

Use a small ice cream scoop and even off the top with a butter knife and deposit batter on a cookie sheet covered with parchment paper. Leave a 2 inch space between each uncooked cake. Bake 15 minutes or until they are firm to the touch. Allow to cook completely.  

Spread with Whoopie Pie filling on side that's flat and make a sandwich. Pressing sides together gently to distribute the frosting evenly. Once cool they can be wrapped individually with plastic wrap. 

To make the Whoopie Pie Filling:

Cream butter with an electric hand mixer and add marshmallow, vanilla and 2 cups of confections sugar. Add more sugar depending on desired consistency.