Step 1

Add the flour, cocoa powder, baking soda, and salt to a large bowl. Set aside.

Step 2

Add the butter to a mixing bowl and beat on high speed until creamy. Add granulated sugar and brown sugar and mix until well combined. Mix in egg and vanilla extract.

Step 3

Add the dry ingredients and mix on low speed until combined. Cover the dough and chill for 30 minutes.

Step 4

Preheat oven to 350 degrees F.

Step 5

Remove the cookie dough from the refrigerator. Line two large baking sheets with parchment paper.

Step 6

Roll the dough into small, 2 teaspoon sized balls. 

Step 7

You should be able to roll about 30 cookie dough balls. I can fit 15 on each of my cookie sheets. Press down lightly on the top of the balls to slightly flatten. 

Step 8

Bake for 6-8 minutes. The will appear soft but will continue to harden as they cool. Cool for 5 minutes on the baking sheet, and then remove to a wire cooling wrack to cool completely.

Step 9

Beat together butter and shortening until smooth. 

Step 10

Add powdered sugar and vanilla and mix for 1-2 minutes, until smooth. 

Step 11

Once the cookies have cooled, add a small spoonful of filling onto the inside of a cookie. Place the inside of another cookie on top and press together.

Step 12

Cookies store well, covered in the fridge, for up to 1 week. They also freeze well, up to 2 months. 

Step 13

Filling can be made up to 1 week ahead of time, stored in the fridge. Allow to come to room temperature before filling cookies.