Instructions

For the Chocolate Cake

1. Preheat oven to 350 degrees. Spray the bottom of the three 8-inch round cake pans with cooking spray and line bottoms with parchment. Set aside.
2. In a large mixing bowl combine the flour, sugar, cocoa powder, baking soda, baking powder, and salt.
3. In a medium bowl or measuring cup, combine the eggs, buttermilk, water, oil and vanilla.
4. With the mixer on low speed, gradually add the wet ingredients to the dry ingredients and mix until smooth, about 30 seconds. Scrape down the sides of the bowl and mix again for another 10 to 20 seconds. Divide batter equally among the three cake pans (about 16 ounces of batter in each pan).
5. Bake the layers for about 18 to 20 minutes (time may vary depending on your oven) or until a wooden pick inserted into the center of the cake comes out with only a few moist crumbs on it. Let the cakes cool in pans on a wire rack for 10 minutes, and then turn onto a rack to cool completely. When completely cooled, wrap the layers in plastic wrap and chill for at least an hour in the freezer. Cakes can be make a week ahead of time and wrapped in plastic wrap. If you'd like to store the cake layers longer than a week, wrap in tin foil, as well, and then place in a zip lock bag.

For the Cookies and Cream Filling

1. In the bowl of a stand mixer fitted with the whisk attachment, whisk the heavy whipping cream on high for about 3 to 5 minutes, until the cream forms stiff peaks. Transfer the cream to another bowl and set aside.
2. In the now empty bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese for a couple minutes until smooth. Gradually add the powdered sugar. Beat for a couple minutes until smooth.
3. Fold in the whipped cream until no streaks of whipping cream remain. Fold in the crushed Oreos. 
4. Best to make right before you assemble the cake so the cookies don't get soggy. If you want to make this ahead of time, just leave out the Oreos until you're ready to assemble.

For the Oreo Buttercream

1. n a stand mixer fitted with a paddle attachment, cream the butter on medium-high speed for about two minutes.
2. With the mixer on low speed, slowly add the sifted powdered sugar until incorporated. Scrape down the sides of the bowl and continue to mix for another minute.
3. Add the heavy cream (one tablespoon at a time). Once the cream is incorporated, increase the speed to medium-high and beat the frosting for five minutes. It should get lighter in texture and color. 
4. Stir in the cookie crumbs.

For the Chocolate Drip:

1. In a microwave safe bowl, heat the cream for about 1 minute. Pour the cream over the chocolate and let sit for about 5 minutes. Mix the chocolate and cream until smooth and shiny. If needed, microwave the mixture for an additional 30 seconds.
2. Add one drop black food gel (optional). This will make the drip as dark as the cookies.
3. Let cool slightly before adding to the cake.
4. Best to add the drip when the cake has been chilled.

Assembly:

1. Place the first cake layer top side up, in the center of the cake board. Pipe a rim of Oreo buttercream around the edge of the cake and then fill the center with about 1 cup of the cookies and cream filling. 
2. Place the second cake layer on top of the buttercream and filling. Repeat piping and filling.
3. Place final cake layer, top side down.
4. Crumb coat the entire cake with a thin layer of the Oreo buttercream and freeze for about 10 to 15 minutes to set this layer of frosting. 
5. Once the crumb coat is set, continue to frost the cake with the remaining frosting. Chill the cake again for another 10 minutes before adding the drip.