Start off by making your cake according to the directions on the box. Swap the water for buttermilk, vegetable oil for butter, add an extra egg and 1 cup chocolate chips. Bake according to directions in 2 parchment-lined round cake pans.
Allow cakes to cool on a cooling rack. Then wrap each cake in saran wrap. Freeze overnight.
Now take one of your cake pans and line it with parchment. Spread as much of your cookies and cream ice cream in that will fit. Cover with saran wrap and return to freezer overnight.
When day 2 comes around, it is time to build your cake! Prep your frosting by smashing about 20 cookies into crumbs. I usually use a ziplock and anything to smash it with. Once you have your crumbs, mix them into the white frosting. Set aside for later.
Start making the ganache. In a pot, add your heavy cream and bring it to a slightly bubbling simmer. Then start to add in your semi-sweet chocolate, stirring in a little bit gradually. Add in the vanilla extract and stir until the chocolate looks smooth.
On your cooling rack place down one of your frozen chocolate cake rounds and remove the parchment paper. Then, grab that ice cream layer from the freezer and carefully flip it on top of the cake layer. After that grab your second layer of frozen cake and put it on top.
On the very top of your cake pipe a round of icing. This can also be used to cover any cracks or unevenness on the sides if necessary. Quickly grab your ganache and evenly poor it all on top of making sure to evenly spread it with a spatula on all sides. Very carefully, use a couple spatulas to slide the cake into the box and right into the freezer. Leave for at least an hour before decorating.
For the decoration, evenly place 8-10 oreos all around the outer edge on top. Slightly off-centered, place a giant gob of your icing so it looks like ice cream. Then slide on your ice cream cone to look like an ice cream cone is sideways on the cake. Finally crush up some large pieces of waffle cone and spread them around the sides of the cake. Return cake box to freezer until it is time to serve.
Serve this up and ENJOY!