Whoopie Pies

1. Preheat oven to 350° F. Line 2 baking sheets with parchment paper or silpat mats.
2. In a large bowl, whisk together the flour, salt, baking powder, and baking soda, and set aside.
3. In another large bowl, whisk together the cocoa and espresso powder.
4. Add the cold brew coffee (or hot freshly brewed strong coffee) and boiling water, whisk until both powders are completely dissolved.
5. In a medium bowl, stir the brown sugar and oil together. Add mixture to the cocoa mixture and whisk until combined. Add the egg, vanilla and buttermilk and whisk until smooth.
6. Using a rubber spatula, gently fold the dry ingredients into the wet ingredients. Make sure to scrape down the sides and the bottom of the bowl as you fold.
7. Use a 2 tablespoon sized ice cream scoop or cookie scoop to drop heaping mounds of the dough onto the prepared baking sheets about 1-inch apart.
8. Bake for 10 to 15 minutes, until the cookies are just starting to crack on top and a toothpick inserted into the center of a cookie comes out clean.
9. Allow to cool on pans.

For The Whiskey Buttercream Filling

1. Whip the butter on medium-medium/high speed in the bowl of a stand mixer until light and fluffy, at least 5 minutes.
2. Whip in a pinch of salt. Then add half of the powdered sugar, one cup at a time.
3. While mixing, slowly pour in the vanilla and whiskey. Then add the remaining powdered sugar until a desired consistency is reached.
4. For these Irish Coffee Whoopie Pies, I like my buttercream like I like my whiskey, stiff. A thicker filling will help hold the pies together.

Assemble The Pies

1. Once the pies are completely cooled, turn half of them over.
2. Use a small offset spatula to spread a tablespoon sized dollop onto the flat side of the pie, don't spread all the way to the edge as the filling will spread a bit out when topped.
3. Place another pie, flat side down, on top of the filling. Gently press down and turn slightly so that the filling spreads to the edges of the pies. Repeat with all of the pies.
4. Store the whoopie pies in the refrigerator for about 30 minutes to firm up before serving.