To Heat Treat Flour

Before baking the cookies, heat treat the flour to be used in the buttercream. Spread the flour onto a clean, dry baking sheet. Use 1/2 cup more than the recipe calls for so to be sure you have plenty. Bake at 300°F for 5-8 minutes, checking every 2 minutes with a digital thermometer. Stir the flour each time you check the temperature and rotate the pan in the oven. Bake until the temperature reaches 165°F and then remove from the oven and cool completely.

For Cookies

1. Place chocolate and butter in a bowl and heat over a double boiler on medium heat. Stir often as the chocolate and butter melt. Once melted, remove from heat and stir until smooth. Pour the melted chocolate and butter mixture into the bowl of a stand mixer fitted with the whisk attachment and allow to cool slightly.
2. In a separate bowl, whisk together flours, cocoa powder, baking powder, baking soda and salt. Set aside.
3. Once the chocolate mixture has cooled slightly, add the eggs, brown sugar and granulated sugar. Mix on medium low speed until well combined. Add the vanilla and stir to combine.
4. Add the dry ingredients to the chocolate mixture and mix the flour is fully incorporated. Do not over mix.
5. Cover the bowl with plastic wrap and chill for 30 minutes.
6. Preheat oven to 350 degrees. Line two baking sheets with parchment paper and set aside.
7. Use a small cookie scoop to measure out cookie dough. For best results, use a kitchen scale to weigh each cookie dough ball. The cookies shown here are .07-.08 ounces each. Place the cookie dough balls on the prepared cookie sheets, about 2 inches apart.
8. Bake for 8-10 minutes or until edges are set and the center of the cookies begin to puff and crack slightly. Do not over bake.
9. Remove the cookies from the oven and and while the cookies are warm, use the inside arch of a fork to nudge the edges of the cookie in toward the center or swirl a round cookie cutter around the outside if the cookies to form the cookies into uniform rounds. Cool on the baking sheet for 8-10 minutes before transferring to a wire rack to cool completely before assembling the sandwiches.
10. To make the sandwiches, pipe a swirl of cookie dough buttercream onto the flat side of one cookie. Top with the flat side of another cookie and gently press together. Top with a sprinkle of flakey sea salt if desired.
11. Place cookie sandwiches in the refrigerator to set if needed. Serve chilled or room temperature.

For Cookie Dough Buttercream

1. In the bowl of a stand mixer fitted with the paddle attachment, cream together the softened butter and brown sugar. Beat until light and fluffy.
2. In a small bowl, whisk together the confectioners sugar and flour. Add to the butter mixture, 1/2 cup at a time while mixing on low speed. Once all of the flour and sugar has been added, increase the speed to medium and beat for one minute.
3. Add the vanilla and salt. Mix to combine well.
4. Add the heavy cream, one tablespoon at a time until the desired consistency is reached. The buttercream should be smooth and fluffy, but firm enough to hold it’s shape when piped.