Preheat the oven to 350F and line your baking sheet with parchment paper.
In your mixer, combine cake mix, cocoa powder, and flour.
Add your melted butter, oil, eggs, buttermilk and vanilla. Mix until a thick dough forms
(The dough should be thicker than brownie batter but softer than a traditional cookie dough)
Using a cookie scoop, scoop large balls of dough. (About 1/4 cup per cookie)
Before baking, use the bottom of your 1/4 cup measuring cup and press down on the center of the cookie (for a place for the frosting to sit).
Bake for 10-12 minutes.
Cool completely before frosting.