- Preheat oven to 400 degrees.
- Line two rimmed baking sheets with parchment paper or Silpat mats
- Sift together flour, cocoa powder, baking soda, baking powder, salt.
- With an electric mixer, beat butter and sugar on medium speed until light and fluffy.
- Add eggs, buttermilk and vanilla.
- Beat until well combined.
- On low speed, slowly add dry ingredients, mix until combined.
- Drop 1 1/2 tablespoons of batter onto baking sheets, spacing 2 inches apart.
- Bake until set, about 8 minutes, rotating halfway through. (Cookies should feel soft but not wet)
- Allow cookies to cool completely on wire rack.
- Put cream cheese and butter in the bowl of an electric mixer fitted with a paddle attachment. Mix on high speed until smooth.
- Reduce mixer speed to low.
- Add vanilla extract.
- Add confectioners' sugar, mix until combined.
- Spread about 1-2 tablespoons of filling on the bottom of one cookie.
- Sandwich with another cookie.