For Cookies

1. Preheat oven to 350 degrees.
2. Line two baking sheets with parchment paper and set aside.
3. In a medium bowl, sift together flours, cocoa powder, hot cocoa mix, baking soda and salt. Set aside.
4. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugars at medium high speed until light and fluffy. The mixture will be pale in color.
5. Add the egg, vanilla, and heavy whipping cream. Mix on low speed until fully combined.
6. Add the hot espresso and mix until incorporated.
7. Add the flour mixture in two batches, scraping down the sides of bowl as needed.
8. Do not over mix.
9. Scoop balls of dough using a large cookie scoop and place them 3 inches apart on the prepared cookie sheets. To ensure all cookies are of equal size, weigh the dough balls first.
10. Bake for 10 minutes or until cookies are flat and firm on the edges. They may look slightly puffy in the center but will flatten and cracks will form as they cool.
11. Let cookies cool for 10 minutes on the cookie sheets before moving to a cooling rack to cool completely.
12. While cookies cool, make the buttercream.

For Salted Caramel Buttercream Filling

1. In the bowl of a stand mixer fitted with a paddle attachment, cream the butter on high speed for 1 minute.
2. Reduce the speed to low and add the confectioner’s sugar one cup at a time, scraping the sides of the bowl after each addition.
3. Once sugar is incorporated, increase the speed to high and mix for 2-3 minutes until light and fluffy.
4. Stop the mixer and add the salted caramel and a pinch of salt.
5. Mix on low until combined and then increase the speed to medium high and whip for 3-4 minutes until light and fluffy, stopping to add a tablespoon or two of whole milk if buttercream is too thick.
6. Scoop buttercream into a reusable piping bag fitted with a star tip and pipe swirls of buttercream onto the bottom side of one cookie. Then top with another cookie. Repeat until all cookies are paired together.