This Oreo Cake is made with three layers of moist and rich chocolate cake, covered in an equally delicious Oreo buttercream frosting. An ultimate cake for chocolate and Oreo lovers!
Brush three 8” cake pans with melted butter. Line the bottom of each cake pan with a piece of round parchment paper and brush the parchment paper with butter as well. Set aside.
Add buttermilk, melted butter, oil, eggs, and vanilla extract to a large bowl. Beat with a whisk until combined.
Sift together flour, cocoa powder, baking soda, and baking powder into a medium mixing bowl. Add sugar and salt to the flour mixture, and mix thoroughly with a whisk. Add the flour mixture to the liquid mixture, and whisk until a smooth batter forms.
Divide batter evenly among the three prepared cake pans, and bake for 25 - 26 minutes until a toothpick inserted in the middle of the cake comes out clean with just a few crumbs attached.
Remove from the oven and let cool on a wire rack for 20 - 30 minutes. When you can comfortably touch the cake pans, use a butter knife to loosen the sides, flip the pan over to remove the cake from the pan. Peel off the parchment paper, and allow the cakes to cool completely on a wire rack before adding frosting.
Make the buttercream
Add butter, cream, and vanilla extract to the stand mixer bowl.
Sift powdered sugar into the bowl.
Stir to incorporate all of the ingredients, then increase the mixer speed gradually to high and beat until the frosting is lighter in color and fluffy, about 5 - 15 minutes
Ground the Oreos finely in a food processor or blender, stir into the buttercream until evenly mixed.
Assemble the cake
Line a cake stand or plate with a few strips of parchment paper around the edges and place 1 layer of cake on top.
Add 1 cup of frosting on top of the first layer and spread it out evenly with a spatula. Repeat this step with the second and third cake layer. So there will be 1 cup of frosting in between each cake layer and also on the top.
Use the remaining frosting to cover the side of the cake or use 1 cup of frosting for the side and reserve 1 cup of frosting for the swirl on top.
If adding swirl decoration on top, add the frosting to a pastry bag fitted with a large open star tip and pipe swirls around the edge. Add Oreo cookies on top between the swirls for additional decoration if you wish.
Use a warm paring knife to separate the bottom of the cake from the parchment paper, wiping as you go, carefully pull out the parchment paper lining the plate or cake stand from the bottom of the cake.
Refrigerate the cake for 2 hours before serving.
Notes
Use a kitchen scale to divide the cake batter if you want to be more precise, about 500 g of batter per pan. This will also help the cake bake evenly.
Use just two 8” cake pans for a 2-layer cake. Note that the cake layers will be much thicker, you’ll want to increase baking time to 30-35 minutes in this case.