Preheat the oven to 350 degrees. Line the bottom and up the sides of an 8x8-inch or 9x9-inch baking pan with foil sprayed with baking spray or line with parchment paper.
Press cookie dough into bottom of the prepared baking pan.
Add a layer of Oreo cookies on top of the cookie dough.
Here's the Oreo cookies I used.
Prepare brownie mix according to box instructions. Pour 2/3 of the brownie batter over the Oreo cookies (bake the remaining brownie batter in a separate pan, if desired).
Here's the brownie mix I used.
Bake until a toothpick inserted in the brownie layer is only slightly gooey, about 35-40 minutes.
Cool brownies completely then prepare ganache.
GANACHE: In a double boiler over simmering water, combine 1/2 cup heavy cream and 1 cup chocolate chips, stir until melted and well combined. Cool for a couple of minutes then pour over brownies.