Oreo Fudge Cake

5 from 1 rating

This Oreo fudge cake is made with moist black cocoa cake layers, Oreo buttercream, and rich milk chocolate ganache. It’s a chocolatey twist on a cookies-and-cream cake that will have you going back for a second slice!

Prep Time45

Cook Time25

Additional Time1

Total Time2 10

Course: Cakes

Cuisine: American

Servings: 24 servings

Calories: 633kcal

Author: Chelsey White

Equipment

Ingredients

Chocolate Ganache Filling

1/2 cup heavy whipping cream 120g
2 cups milk chocolate chips 360g
1/4 cup unsalted butter, room temperature 56g
2 Tbsp light corn syrup - optional 40g
1/2 tsp fine salt 3g

Black Cocoa Cake Layers

2 cups all-purpose flour 260g
2 cups granulated sugar 400g
3/4 cup dark or black cocoa powder, sifted 75g
2 tsp baking powder 8g
1 1/2 tsp baking soda 9g
1 tsp instant coffee or espresso, optional
1 tsp fine salt 6g
1 cup water, warm 240g
1 cup buttermilk, room temperature 240g
1/2 cup vegetable or canola oil 110g
2 large eggs, room temperature 112g
1 tsp vanilla extract or vanilla bean paste 4g

Oreo Buttercream

2 cups (4 sticks) unsalted butter, room temperature 454g; 1 lb. box
1 Tbsp clear vanilla extract or vanilla extract 12g
1/2 tsp fine salt 3g
5 cups powdered sugar 625g
1/4 cup + 2 Tbsp heavy whipping cream, room temperature, divided 90g
1 1/2 cups Oreos or chocolate sandwich cookies, roughly chopped (12 regular Oreos) 135g
1/3 cup unsweetened cocoa powder 33g
1 cup milk chocolate, melted and cooled 170g

Instructions

Chocolate Ganache Filling

This ganache needs at least 1 hour to cool and thicken, but I usually make it the night before. Heat 1/2 cup of heavy cream in a heatproof bowl in the microwave for 45 seconds, until it just begins to bubble and steam. If you don't have a microwave, you can also use a double boiler to heat the cream.
Gently pour 2 cups of milk chocolate chips into the heavy cream. Make sure the chips are fully covered with cream. Let the mixture sit for 1 minute. If you want to use dark (60-65% cocoa) chocolate chips, use 1 1/3 cups (240g) and 1 cup of heavy cream.
Stir slowly until the cream and chocolate combine and the mixture is smooth. If any bits of chocolate aren't fully melted, heat the mixture again for 10 seconds and stir until smooth.
Then mix in 1/4 cup of room temperature unsalted butter, 2 Tbsp corn syrup (optional), and 1/2 tsp fine salt until combined.
Cover with plastic wrap to prevent the ganache from forming a skin, then set aside to cool to room temperature. You can pour the mixture into a shallow, wide tray to help it cool faster if you're in a rush.

Black Cocoa Cake Layers

Preheat oven to 350°F/175°C. Line three 8-inch cake pans with parchment paper rounds and spray the sides with nonstick baking spray. Set aside.
Sift or whisk together 2 cups flour, 2 cups granulated sugar, 3/4 cup black or dark cocoa powder, 2 tsp baking powder, 1 1/2 tsp baking soda, 1 tsp fine salt, and 1 tsp instant espresso or coffee (optional) in a large bowl. Set aside.
In a separate, large bowl, add 1 cup warm water, 1 cup buttermilk, 1/2 cup oil, 2 eggs, and 1 tsp vanilla and whisk together until fully incorporated.
Whisk the dry ingredients into the wet ingredients until they're just combined, and the batter is smooth.
Pour the batter evenly (about 475g per pan if you're making 3 layers) between the 3 cake pans. Bake for 24-26 minutes or until a toothpick comes out with a few moist crumbs.
Let the pans cool for 10 minutes, then run a small offset spatula around the perimeter of the pan to separate the cake from the pan.
Place the cake pans into the freezer for 30 minutes to accelerate the cooling process. This helps lock in the steam and makes the layers extra moist. If you don't have room in the freezer, place the cake pans on a wire rack and let them cool fully before removing them.
Once the layers are fully cooled, carefully flip the pans and remove the layers. These cake layers bake up pretty flat, so leveling them is optional, but I like to level them with a serrated knife to make the cake easier to fill and frost.
If you make these cake layers in advance, let them thaw for about 15 minutes before making the cake. The cake layers should still be slightly cold to the touch, which will make it easier to assemble the cake.

Oreo and Chocolate Buttercream

Beat 2 cups of unsalted butter on medium speed for 30 seconds until smooth in a large bowl with a hand mixer or the bowl of a stand mixer with a paddle attachment. Then mix in 1 Tbsp vanilla bean paste or vanilla extract and 1/2 tsp salt on a low speed.
Gradually add in 5 cups of powdered sugar while mixing slowly on the lowest setting. Halfway through, add 1/4 cup of heavy cream (save the remaining 2 Tbsp for the last step) to make it easier to mix. I like to place a kitchen towel over my mixer to contain any powdered sugar clouds.
Mix on low until the ingredients are fully incorporated and the desired consistency is reached. Scrape the sides and bottom of the bowl as needed with a rubber spatula. If the frosting is too thick, add additional cream (1 Tbsp at a time). If the frosting is too thin, add more powdered sugar (a quarter of a cup at a time).
Scoop half (about 550g) of the frosting into a separate bowl and fold in 1 1/2 cups of roughly chopped Oreos. If you're making this ahead of time, wait to fold in the Oreos until right before you assemble the cake.
Mix 1/3 cup of unsweetened cocoa powder and the remaining 2 Tbsp of heavy cream into the other half of the frosting (the non-Oreo frosting) on a low speed. Then mix 1 cup of milk chocolate that's been melted and cooled into the frosting on low speed until combined. Scrape the sides and bottom of the bowl as needed. Cover both flavors of frosting flush with plastic wrap to prevent them from crusting, unless you plan to use them immediately.

Oreo Fudge Cake Assembly

Place the first cake layer on a greaseproof cake board or large flat plate, using a small dab of buttercream to keep it in place.
Spread half of the room-temperature chocolate ganache on the first cake layer, then spread half of the Oreo buttercream on top of the ganache. Try to keep the filling relatively even so the next cake layer sits flat. Add the second cake layer and repeat this process, then place the final cake layer upside down (this makes it easier to frost). Chill the cake for about 15 minutes in the freezer or 30 minutes in the fridge, or until the filling is firm.
Then cover the cake in a thick layer of chocolate buttercream. Use a large offset spatula or the back of a spoon to create a textured look around the cake. Top the cake with a ring of chopped Oreos and enjoy.

Video

Notes

I highly recommend making your cake layers in advance and freezing them. It breaks the process up and makes it more approachable.

You can make the frosting ahead of time, too, or save any leftover frosting! It can be stored in an airtight container in the fridge for up to a week or in the freezer for up to 3 months. Be sure to give it a good stir once it thaws to get the consistency nice and smooth again.

A frosted cake can last in the fridge for up to a week, or in the freezer for up to a month. The buttercream locks in all the moisture, keeping the cake fresh and delicious!

Let the cake sit at room temperature before serving so the buttercream and ganache have time to soften.

Nutrition