Preheat oven to 325 degrees. Line a 9x9 baking pan with parchment paper and set aside.

Prepare brownie mix as stated on box adding all ingredients required. Fold in chopped oreos and spread batter in prepared baking pan. Bake brownies for 30-35 minutes or until a toothpick inserted in the center comes out slightly moist still with some batter on it. (This is what makes brownies fudgy!) I usually bake my brownies 10 minutes shorter than the time stated on the box. Once brownies are down, set them on a wire rack still in the pan to cool completely. I place mine in the refrigerator to speed this step up.

While brownies are cooling, prepare ganache glaze. Place chocolate chips in a large bowl, set aside. In a small saucepan, heat cream until very hot. Pour heavy cream over chocolate chips and shake the bowl to completely immerse them. Let sit for about 5 minutes without touching then whisk until they chocolate becomes velvety smooth. You want it to have a slightly thick consistency to ensure it is going to set up. Measure peanut butter and microwave for a couple of seconds to melt slightly only until pourable. (The thicker it is, the harder it is going to be to swirl but you don't want it to be too thin and run.)

Once brownies are completely cooled, pour chocolate ganache on top and spread to distribute. Pour peanut butter in 4 vertical lines across the pan. Swirl knife through the vertical lines horizontally, creating a swirled effect. Cover and place brownies in the refrigerator so the glaze has time to set up, about 2-3 hours. Take out 30-45 minutes before serving to let them come to room temperature.

Brownies stay fresh for up to 4 days stored in an airtight container.