Preheat your oven to 325 degrees F. Spray three 8-inch or four 6-inch round cake pans with cooking spray and then line with parchment. Spray again. Set aside.
Place the Oreo cookies in a food processor or blender and pulse until the Oreos are finely ground.
In a medium-size bowl, combine the Oreo crumbs, sugar and melted butter. Stir until all the Oreo crumbs are dampened by the melted butter. You should be able to scoop by hand and have it all stick together.
Divide the mixture evenly between the pans and press down firmly with your hand or the back of a flat measuring cup
Bake for 10 minutes. Let the crusts cool while you make the cake layers.
For the cake
Keep your oven at 325.
In a medium size bowl whisk together the cocoa powder, baking powder, baking soda, salt and all-purpose flour. Set aside.
In a bowl of a stand size mixer fitted with the paddle attachment, cream the butter, oil and sugar on medium high speed until light and fluffy. About 4 minutes. The mixture should turn white and double in size.
With a rubber spatula, scrape down the sides and the bottom of the bowl. With the mixer on medium speed, start adding the eggs one at a time, mixing for 30 seconds after each addition. Scrape the sides and bottom after each addition.
Once the eggs have been added, add the vanilla, LorAnn’s emulsion (or red food coloring), sour cream, and vinegar mix on low just until incorporated about 30-60 seconds.
Scrape down the sides of the bowl and turn the mixer on low and add half of the flour mixture and half of the buttermilk to the butter mixture and mix until just incorporated. Finally, add the rest of the flour mixture and the last of the buttermilk, while mixing on low. Do not over mix, this should take 30-45 seconds.
Once mixed, evenly divide all of the batter into the prepared pans with the Oreo crust (about 18 ounces in each 8-inch pan) Bake for 33-35 minutes. I checked mine at 33 minutes and it needed about one more minute. Insert a toothpick and if it comes out clean or with only a few crumbs, your cake is done.
Allow the cakes to cool in the pans for 15 minutes and then remove them from the pans and transfer them to a wire rack and let them come to room temperature. Wrap them in plastic wrap and either freeze or refrigerate them.
For the cream cheese filling
In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese for a couple minutes until smooth. Scrape down the sides and beat for 2 more minutes. With the mixer on low, add the granulated sugar. Beat on high for a couple minutes until smooth. Place in a medium sized bowl.
In the same bowl of a stand mixer fitted with the whisk attachment, whisk the heavy whipping cream, and vanilla on high for about 5-7 minutes, until the cream forms stiff peaks.
Fold the whipped cream into the cream cheese mixture until no streaks of whipping cream remain. Making sure not to over mix.
This will hold for a couple of hours at room temperature. If you won’t be using it right away, store in an airtight container in the fridge for up to 2 days.
For the buttercream
In a stand mixer fitted with a paddle attachment, cream the butter on medium-high speed for about two minutes.
With the mixer on low speed, add all of the sifted powdered sugar at once and mix on low just until incorporated. With a rubber spatula, scrape down the sides of the bowl.
Add the heavy cream, salt and vanilla, increase the speed to medium-high and beat the frosting for five minutes. It should get lighter in texture and color.
With the rubber spatula, gently stir in the cookie crumbs until you start seeing gray streaks.
Assembly
Place the first cake layer top side up on the cake board. With the Oreo crust on top of the cake board. Pipe a rim of Oreo buttercream around the edge of the cake. Fill the center of the cake with the cream cheese filling, making sure not to over fill, I used a little under 1 cup.
Place the second cake layer, crust side down, on top of the buttercream and filling. Repeat piping and filling.
Place final cake layer, crust side down, on the filling.
Apple a thin layer of the Oreo buttercream, also known as the crumb coat, and freeze for about 10 to 15 minutes to set this layer of frosting.
Once the crumb coat is set, continue to frost the cake with the remaining frosting.
Serve at room temperature, wrap leftover cakes slices in plastic wrap and will hold in the fridge for a couple days.