1. Preheat oven to 350 degrees and line pans with cupcake liners.

2. Sift cake mix into a small bowl to remove lumps and set aside.

3. In a large bowl, gently whisk eggs, oil, milk, sour cream and vanilla extract together.

4. Add cake mix and stir until smooth.

5. Fold in chopped oreos.

6. Fill cupcake liners 3/4 full (they won't rise quite as much as normal cupcakes because of the Oreo pieces).

7. Bake for 17-22 minutes, or until an inserted knife comes out clean.

8. Let cool.

9. Frosting: Beat butter and vanilla extract. Add cocoa powder and slowly add powdered sugar until you reach your desired consistency. Add brownies (crumble them first) and beat only until the brownies are covered in frosting.

10. Frost your cupcakes using a knife or a #809 piping tip and top with pieces of Oreo.