For the cookies:
3/4 c. almond flour
1/3 c. black cocoa powder
1/3 c. granulated Swerve/sweetener
2 tbsp. coconut flour
1 tsp. kosher salt
1/2 tsp. (gluten-free) baking powder
1/3 c. vegetable oil
1 large egg
1 tsp. pure vanilla extract

For the filling:
1/2 c. (1 stick) butter, softened
3/4 c. powdered Swerve/sweetener
1 tsp. pure vanilla extract

Make cookies: In a large bowl, mix together almond flour, cocoa powder, Swerve, coconut flour, salt, and baking powder. Add oil, egg, and vanilla and mix until combined. Shape into a disc, then wrap in plastic wrap and refrigerate until firm, 2 hours.
Preheat oven to 350° and line a large sheet tray with parchment paper. Lightly dust a clean surface with cocoa powder and roll out dough ¼" thick. Cut out cookies with a 2" round cookie cutter.
Place cookies on prepared baking sheet. Bake until slightly firm to the touch, about 14 to 16 minutes. Let cool.
Make filling: In a large bowl using a hand mixer, beat butter until smooth. Add Swerve and beat until combined, then mix in vanilla.
Spread filling on one side of cookie and place a second cookie on top. Repeat with remaining cookies