Using a food processor blend Oreo into small and medium pieces. Then, blend the Oreos to a crumb. Set aside. In a medium mixing bowl, sift the flour, cocoa powder, baking soda, and salt.
2 1/4 cups All-purpose flour, 1/2 cup Unsweetened cocoa powder, 1 tsp Baking soda, 3/4 cup Oreo pieces, 1/2 cup Oreo crumbs, 1 tsp Salt
Using a mixer in a separate bowl, beat the melted butter (make sure it is cooled before using), brown sugar, and sugar on high speed for 2 minutes.
1 cup Unsalted butter, 1 cup Brown sugar, 1/2 cup White granulated sugar
Add in the vanilla and eggs. Mix on medium until combined. Add in the dry ingredients and mix on low speed until just combined.
1 tsp Pure vanilla extract, 2 Large eggs
Add in the Oreo pieces and Oreo crumbs. Mix until just combined.
Preheat the oven to 350°F. Line two cookie sheets with parchment paper. Let the cookie dough rest in the bowl for 10 minutes to help with spreading.
Use a large cookie scoop (about 2 TBSP) to scoop the cookie dough. Place 6 cookie dough balls per cookie sheet.
Bake one cookie sheet at a time. Bake for 12-14 minutes.
Let the cookies sit on the hot pan for 5 minutes before transferring to a cooling rack. Cool the cookies completely before decorating.