Step 1

Preheat the oven to 350 degrees F/175 degrees C.

Step 2

Grease a 9x9 baking dish with cooking spray, oil, or butter and line with parchment paper.

Step 3

Carefully spread the cookie dough into the pan, pressing down into an even layer.

Step 4

Top the cookie dough with an even layer of whole, uncut Oreos.

Step 5

Make the brownie batter according to the instructions on the box.

Step 6

Pour the brownie batter over the Oreos and cookie dough, careful not to disturb the Oreos.

Step 7

Bake for 40 to 45 minutes, checking after 40 with a toothpick in the middle.

Step 8

Allow the pan to cool for 15 minutes before carefully lifting it out and cutting it into squares.