Preheat oven to 375ºF and place rack in center of the oven. Line cookie sheets with
parchment paper. In a large bowl, sift together flour, cocoa powder, baking powder, baking
soda and salt. In the bowl of an electric mixer fitted with the paddle attachment, beat
the butter and sugar until light and fluffy. Add the egg beating well. Beat in the vanilla
extract. In a small measuring cup, mix the buttermilk and coffee mixture. With the mixer
on low speed, alternately add the flour mixture and buttermilk/coffee mixture, in three additions,
beginning and ending with the flour. Using a cookie scoop, drop batter onto cookie
sheet spacing 2-inches apart. With moistened fingers or with the back of a spoon, smooth
the tops of the cookies. Bake for 9-10 minutes or until the tops of the cookies, when
lightly pressed, spring back. Remove from oven and transfer to a wire rack to cool completely.
Once cookies are cool, spread or pipe, flat side of one cookie, with marshmallow
filling and top with another cookie, flat side down. Roll edges of whoopie pies in crushed
peppermint chips. Store in an airtight container in refrigerator for up to 1 week.
Marshmallow Filling Instructions: In the bowl of an electric mixer fitted with the paddle attachment, beat together the
marshmallow crème and shortening, starting on low and increasing to medium speed until
the mixture is smooth and fluffy, about 3 minutes. Reduce speed to low, add confectioner’s
sugar and vanilla. Beat until incorporated. Increase mixer speed to medium and
beat until fluffy, about 3 minutes.