Ingredients  

1. 1 Box Brownie Mix, plus ingredients needed to make it
2. ½ cup semi-sweet chocolate chips
3. 2 cups heavy cream
4. 1 (14 oz) can sweetened condensed milk
5. 1 teaspoon vanilla
6. 15 Oreos, coarsely chopped
7. 1 cup semi-sweet chocolate chips
8. 4 Tablespoons corn syrup
9. ½ cup heavy cream
10. 12 Oreos, coarsely chopped
11. 2 cups heavy cream
12. ⅓ cup powdered sugar
13. 2 teaspoons vanilla
14. 3 Oreos, finely-crushed
15. ⅔ cup semi-sweet chocolate chips
16. ½ cup heavy cream
17. 12 Oreos

Instructions 

1. Preheat the oven to 350ºF. Line an 8-inch cake pan with parchment paper; spray with nonstick cooking spray.
2. Prepare brownie batter according to the instructions on the back of the box. Stir in the chocolate chips. Pour batter into prepared pan, and bake for 37-45 minutes, or until a toothpick inserted in the center comes out with few crumbs attached. Allow to cool completely.
3. Line an 8-inch cake pan with plastic wrap, leaving overhang on the sides.
4. In the chilled bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream until stiff peaks form.
5. Add the sweetened condensed milk, vanilla, and chopped Oreos. Fold everything together until just combined.
6. Pour ice cream mixture into prepared pan, and spread evenly with a spatula. Get rid of any air bubbles by lifting the pan 1-2 inches above the counter and dropping it. This will also create a more even layer. Chill in the freezer for at least 4 hours, or until completely hardened.
7. Place the chocolate chips and corn syrup into a medium bowl.
8. Pour heavy cream into a glass measuring cup and heat in the microwave until it begins to simmer. Check it every 15-30 seconds so that it doesn’t bubble over.
9. Pour hot cream over chocolate chips, and allow to sit for a few minutes. Stir until completely smooth. Stir in the chopped Oreos. Allow to cool to room temperature.
10. Once the ice cream has hardened, spread the fudgey Oreo filling evenly on top. Place the brownie on top, then pull up the sides of the plastic wrap to wrap the whole cake. Return to the freezer for at least 6 hours.
11. In the chilled bowl of a stand mixer fitted with a whisk attachment, beat the heavy cream until soft peaks form. Add the powdered sugar and vanilla, and continue beating until stiff peaks form.
12. Unwrap the frozen cake, and invert it out of the pan onto a serving plate. Remove the plastic wrap from the top of the ice cream.
13. Frost the cake with a thin layer of whipped cream–this will be the crumb coat. Be sure to work quickly so that the ice cream doesn’t melt. Place cake back into freezer for about 30 minutes to firm up. Remove cake from the freezer and frost with a second and final layer of whipped cream. Return cake to freezer.
14. Stir the 3 finely-crushed Oreos into the rest of the whipped cream, and transfer to a piping bag fitted with a star tip. I used Wilton’s 1M tip.
15. Make the ganache by placing the chocolate chips into a medium bowl; set aside. Pour heavy cream into a glass measuring cup, and heat in the microwave until it just begins to boil. Pour hot cream over the chocolate chips, cover with plastic wrap, and allow it to sit for 4-5 minutes. Remove plastic wrap, and stir until smooth. Allow to cool to room temperature.
16. Remove cake from the freezer, and drizzle the chocolate ganache along the top edges of the cake, allowing the ganache to dribble down the sides. Spread the rest of the ganache evenly on top of the cake. Return cake to freezer for 5 minutes to set ganache.
17. Using the Oreo whipped cream, pipe rosettes on top of the cake along the border. Insert Oreo cookies between the rosettes. Serve immediately or store in the freezer.