Preheat oven to 350 and line cookie sheet with parchment paper
Combine flour, cacao, baking soda, and salt
In a separate bowl combine remaining wet ingredients with a hand or stand mixer. Then add your dry ingredients in and combine until dough-like texture is achieved
Roll into balls and place at least an inch apart on a baking sheet. I got 14 cookies, so I did 2 batches, assuring the cookie balls weren't too close together
Bake for 7-8 minutes. Let cool for 5 min, then transfer to wire cooling rack
Use your hand or standing mixer to combine buttercream ingredients until whipped, several minutes
Place buttercream on 7 of your cookie halves, then top with remaining cookies. Pipe remaining buttercream on top for your signature fudge stripe design
Place cookies in the fridge for an hour to allow the cream centers to set
Enjoy!