for the cookies and cream cheesecake layer:
Preheat the oven to 325 degrees. Line the bottom of an 8” springform pan with parchment paper and wrap the bottom half of the pan in tinfoil. In the bowl of an electric mixer beat the cream cheese until smooth and fluffy, then slowly add the sugar. Beat in the vanilla and salt until smooth. Add the eggs one at a time, scraping down the sides between each addition and beating well. Mix in the sour cream and gently fold in the chopped Oreos.
Place springform pan into a larger pan and pour boiling water until it comes up halfway up the sides of the springform pan. Bake for about 45 minutes, or until the center is just set. Remove pan from water and allow it to cool for 20 minutes. Run a knife around the edge of the pan and set aside to cool completely. Remove outer ring of pan, leaving the bottom piece, wrap cheesecake with plastic wrap, and store in the freezer until ready to assemble.
for the chocolate cake layers:
Preheat the oven to 350 degrees. Prepare you 8″ cake rounds by greasing and flouring them. Whisk together the flour, sugar, cocoa, baking soda, baking powder, and salt together in a large bowl until well combined.
In the bowl of an electric mixer, combine the buttermilk, oil, eggs, and vanilla and beat until well mixed. With the mixer on low speed, slowly add the dry ingredients into the wet. With the mixer still on low, add the coffee and stir just to combine. The batter will be very thin, don’t worry!
Split the batter into the prepared pans and bake for 35-40 minutes, or until a cake tester comes out clean. Cool in pans for 30 minutes, then turn onto a cooling rack to cool completely. Level the cakes with a serrated knife if necessary. You can wrap the layers in plastic wrap and store in the freezer until ready to use. (Storing in the fridge will dry the cakes out)
for the cookies and cream frosting:
In the bowl of an electric mixer, beat together the butter and cream cheese for 2-3 minutes, until light and fluffy. Add the vanilla and continue beating. Reduce the mixer’s speed to low and slowly add the powdered sugar. Once incorporated, add the milk and increase the speed to medium. Beat for another 1-2 minutes until smooth. Turn off the mixer and gently fold in the whipped cream and crushed Oreos with a rubber spatula.
Place one layer of the chocolate cake down onto a cake round, or the plate you intend on serving the cake on. Cover layer with a thin layer of frosting, then place the cheesecake layer on top. Spread another thin layer of frosting and place the second chocolate cake layer on top. Cover the entire cake with a thin layer of frosting and place in the fridge for about 10 minutes to allow your crumb coat to set. Once set, cover the cake with another layer until the edges are fully covered and smooth.
Sprinkle Oreo crumbs onto the top of the cake. Load whipped cream into a piping bag with a large star tip and pipe evenly spaced dollops around the outer edge. Top each dollop with a halved Oreo. If your cheesecake layer was frozen for storage, allow the cake to sit out on the counter for an hour or in the fridge overnight to thaw. I actually froze the entire cake in a cake box once completed and took it down the night before and the consistency was perfect.