Make the Brownie Base:

1. Grease an 8×3 inch springform cake pan and line the bottom of it with parchment paper to allow for easy removal. (See note below if you don’t have a springform pan.)
2. Make brownie batter according to instructions on back of box and bake in prepared pan.
3. When brownie is done baking, allow to completely cool.
4. Once cool, remove the brownie base from the pan.
5. NOTE: When it’s time to assemble the cake, you’ll be using the same 8 inch springform cake pan you used to bake the brownie in. Take the time to wash and dry it now so that the pan is ready when you begin assembling the cake.

Make the Ice Cream Layers:

1. When the brownie base is cool, make the ice cream. In a large mixer bowl, combine the softened cream cheese, sugar and brown sugar and mix until smooth.
2. Add the milk and vanilla extract and mix until smooth. Set aside.
3. In another mixer bowl, add the cold heavy whipping cream and powdered sugar and whip on high speed until stiff peaks form.
4. Gently fold about 1/3 of the whipped cream into the cream cheese mixture until combined, then fold in the remaining whipped cream.
5. Divide the ice cream mixture evenly between two bowls.
6. To one bowl, add the chocolate chip cookie crumbs, chopped chocolate chip cookies and mini chocolate chips. Fold to combine. Set aside.
7. To the other bowl, add the Oreo crumbs and chopped Oreos. Fold to combine. Set aside.

Make the First Batch of Ganache:

1. Make a small batch of chocolate ganache to use as a layer between the different flavors of ice cream. Add 3 oz of the chocolate chips to a small bowl (see my tips for making chocolate ganache).
2. Then heat 1/4 cup of the heavy whipping cream in a small microwave safe bowl until it begins to boil. Pour the hot cream over the chocolate chips and allow the mixture to sit undisturbed for 3-4 minutes. Whisk until smooth and set aside.

Build the Cake:

1. Line the sides of your clean, dry 8 inch springform pan with parchment paper. The parchment paper should stick up above the top edge of the pan, since the cake will probably be a little taller than your pan (see example). If you want, put a cardboard cake circle in the bottom of the pan. (See note below for directions of how to prep a standard 8 inch cake pan or use a cake collar.)
2. Place the cooled brownie base back into the prepared pan.
3. Add the chocolate chip cookie ice cream to the top of the brownie and spread into an even layer.
4. Cover with a layer of chocolate ganache and spread into an even layer.
5. Add the Oreo ice cream to the top of the ganache and spread into an even layer.
6. Freeze the cake for 6-8 hours or overnight until frozen through. 

To Finish the Cake:

1. Once the cake is fully set and frozen, prepare the toppings for the cake. Chop or crumble brownies, Oreos and chocolate chip cookies. Set aside.
2. Make the second larger batch of chocolate ganache by placing the remaining 6 oz of chocolate chips into a small bowl.
3. Heat the remaining 1/2 cup of heavy whipping cream in a small microwave safe bowl until it begins to boil, then pour it over the chocolate chips. Allow the mixture to sit undisturbed for 3-4 minutes, then whisk until smooth. Set aside.
4. Make the chocolate whipped cream by adding the heavy whipping cream, powdered sugar and cocoa powder to a large mixer bowl. Whip on high speed until stiff peaks form.
5. Place the chocolate whipped cream into a piping bag and set aside. 
6. Now you can remove the frozen cake from the pan and peel away the outer wrapping of parchment paper (or plastic wrap or cake collar, if used).
7. Drizzle the ganache around the edge of the cake. I used a squeeze bottle, but you could also use a spoon. See my Chocolate Drip Cake post for tips on how to drizzle ganache. 
8. Once you have a ring of drizzled ganache around the outside of the top of the cake, fill in the center of this ring with ganache until the top of the cake is fully covered. Use an offset spatula to smooth out the ganache into an even layer.
9. Pipe a small dome of chocolate whipped cream onto the center of the top of the cake. The whipped cream will act as a sort of glue to help fix your other toppings in place.
10. Cover the dome of chocolate whipped cream with additional brownie chunks, Oreos, chocolate chip cookies and chocolate chips.
11. Place cake in the freezer and keep well covered until ready to serve. Allow it to sit out at room temperature and soften for about 30 minutes before cutting slices. Then serve promptly and return leftovers to the freezer as soon as possible. Best if eaten with 4-6 days.