Oreo Fudge Cake

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!

This Oreo Fudge Cake at a Glance

• Yield: One 3-layer, 8-inch cake
• Serves: About 24
• Cake layers: Moist black cocoa cake
• Filling: Milk chocolate ganache and Oreo buttercream
• Skill level: Intermediate
• Make ahead: Yes! I highly recommend making the components in stages.

How to Make This Oreo Fudge Cake

To make sure this cake turns out as amazing as possible, let’s walk through each step together!

I highly recommend reading through the entire recipe before you start. There are several components, and a little planning makes this recipe so much easier to tackle.

Step 1: Make the Chocolate Ganache Filling

I recommend making the ganache first because it needs time to cool and thicken. I usually make it the night before, but you can also make it a few hours in advance.

Heat the heavy cream until it just begins to bubble and steam, then pour in the milk chocolate chips. Make sure the chocolate is fully covered by the cream and let the mixture sit for about a minute.

Slowly stir until the chocolate and cream come together into a smooth, glossy mixture.

Mix in the room-temperature butter, optional corn syrup, and salt. The corn syrup helps make the ganache extra smooth and glossy, but the recipe will still work without it.

Cover the ganache with plastic wrap and let it cool to room temperature. If you’re short on time, pour it into a shallow container so it cools more quickly.

My biggest tip here is not to rush the cooling process. Warm ganache will be too thin to use as a cake filling and can make the layers slide.

Step 2: Bake the Black Cocoa Chocolate Cake Layers

Next, make the black cocoa cake batter following the recipe card at the bottom of this post.

Whisk the dry ingredients together in one bowl and the wet ingredients together in another. Add the dry ingredients to the wet ingredients and mix just until the batter is smooth and combined.

Divide the batter evenly between the three prepared pans. I recommend using a kitchen scale and adding about 475g of batter to each pan. This helps the cake layers bake to the same height and makes the finished cake easier to stack.

Bake for 24 to 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 edge of each pan.

Place the cake pans in the freezer for about 30 minutes to speed up the cooling process. This helps lock in steam and keeps the cake layers extra moist.

If you don’t have room in your freezer, let the cake layers cool completely on a wire rack before removing them from the pans.

Once the layers are fully cooled, carefully remove them from the pans. These cake layers usually bake up pretty flat, so leveling them is optional. However, I like to trim them with a serrated knife if needed to make the cake easier to stack and fill.

Step 3: Make the Oreo & Chocolate Buttercream

Then it’s time to work on the buttercream! Beat the 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. Mix in the vanilla and fine salt on a low speed.

Gradually add in the 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 of the frosting into a separate bowl and fold in the finely chopped Oreos. If you’re making this ahead of time, wait to fold in the Oreos until right before you assemble the cake.

Mix the unsweetened cocoa powder and the remaining heavy cream into the other half of the frosting (the non-Oreo frosting) on a low speed.

Then mix the melted and cooled milk chocolate 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.

How to Assemble This Oreo Fudge Cake

Once all the components are ready, it’s time to put everything together.

Step 1: Add the Fillings & Repeat

Stack and frost the cake layers on a greaseproof cake board or large flat plate. Use a small dab of frosting to help keep the first cake layer in place. Spread half of the room-temperature chocolate ganache over the 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).

Step 2: Chill and Frost the Cake

Chill the cake for about 15 minutes in the freezer or 30 minutes in the fridge, or until the filling is firm. This helps prevent the cake layers from shifting.

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.

Substitutions and Swaps

This recipe has several components, so I know you might not have every ingredient on hand. Below are the swaps I’d recommend.

Black Cocoa Cake Layers

• All-Purpose Flour: This recipe turns out best with all-purpose flour. However, you can use a good gluten-free 1:1 baking flour blend if needed. I recommend mixing the batter slightly longer and letting it rest for about 20 minutes before baking when using a gluten-free blend.
• Granulated Sugar: I don’t recommend reducing the sugar or changing the type of sugar. Sugar affects both the moisture and texture of the cake layers.
• Black Cocoa: I use black cocoa made by King Arthur, which I order on Amazon. Dark or Dutch-processed cocoa powder will work in this recipe too. In a pinch, you can also use regular unsweetened baking cocoa, but the flavor won’t be quite the same.
• Buttermilk: Full-fat yogurt, sour cream, whole milk, or a nondairy milk can be used in its place.
• Vegetable Oil: Any neutral-flavored oil will work. Canola or sunflower oil are great alternatives. I don’t recommend olive oil because its flavor can come through in the finished cake.
• Eggs: This recipe turns out best with large eggs. If needed, you can experiment with a commercial egg replacer, but the texture may differ.

Milk Chocolate Ganache

• Milk Chocolate: Milk chocolate creates a sweeter, fudgier filling, but if you prefer dark chocolate for a richer and less sweet filling, use 1 1/3 cups or 240g dark chocolate chips with 1 cup of heavy cream.
• Corn Syrup: This is optional. It makes the ganache extra smooth and glossy, but can be omitted.
• Unsalted Butter: Salted butter can be used if needed. Reduce or omit the additional salt to taste.

Oreo & Chocolate Buttercream

• Unsalted Butter: Salted butter can be used in the buttercream, but I recommend reducing the added salt.
• Clear Vanilla: Clear vanilla helps make the Oreo frosting taste like the inside of an Oreo. However, if you don’t have any, you can use regular vanilla in its place.
• Milk Chocolate: This buttercream is very forgiving, so you can mix in any type of chocolate you prefer. Semi-sweet or dark chocolate would work great too.

Black Cocoa vs. Dark Cocoa

Black cocoa gives these cake layers their dark color and makes them taste like an Oreo cookie. Dark cocoa or Dutch-processed cocoa powder can also be used in this recipe, but the cake layers won’t be quite as dark or have as strong of an Oreo flavor.

Regular unsweetened baking cocoa will work in a pinch, but it will give the cake a lighter color and a more classic chocolate cake flavor.

Making This Oreo Fudge Cake in Different Sizes

One batch of chocolate cake batter makes three 8-inch cake layers, with about 475g of batter per pan.

Because this uses the same chocolate cake base as my other layer cakes, you can also use the batter to make two 9-inch cake layers or four 6-inch cake layers.

The bake time will be a bit longer for both of these options and will vary depending on the size and depth of your cake pans, so use the visual cues in the recipe rather than relying only on the timer.

Because this cake has both ganache and buttercream, keep in mind that smaller-diameter cakes can become very tall. I recommend chilling the cake well during assembly if needed.

Can This Oreo Fudge Cake Be Made in Advance?

Yes! In fact, I highly recommend making this cake in stages. There are several components, and breaking up the process can make it feel a lot more manageable.

Chocolate Ganache

The ganache is one of the best components to make ahead of time. It needs at least an hour to cool and thicken, and I often make it the night before.

Store it covered in the fridge, then let it soften at room temperature for a few hours until it reaches a spreadable consistency before assembling the cake.

Black Cocoa Cake Layers

The cake layers can be baked in advance and frozen. Once they’re fully cooled, wrap them tightly with plastic wrap and freeze until needed. Let them thaw for about 15 minutes before assembling the cake.

I actually prefer stacking cakes with slightly chilled layers because they’re easier to handle and create fewer crumbs.

Oreo & Chocolate Buttercream

The frosting can also be made ahead of time and stored in an airtight container in the fridge. Let it return to room temperature, then mix it again until it’s smooth. Frosting usually develops lots of little air bubbles as it thaws, and it helps to give it a good stir before using it.

Assembled Cake

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, which keeps the cake fresh and delicious.

Let the cake sit at room temperature before serving it so the buttercream and ganache have time to soften, and so that you can cut slices more easily.

Frequently Asked Questions

Can I halve this cake recipe?

Yes. A half batch works well when you want a smaller cake. I’d recommend dividing it between three 6-inch pans. The layers will be a tiny bit thinner than the original recipe.

If you make layers this size with a half batch of batter, I’d recommend checking on them a couple of minutes early as they bake!

Can I use dark chocolate instead of milk chocolate in the ganache filling?

Yes, but you need to adjust the ganache ratio. For a dark chocolate ganache made with 60 to 65% cocoa chocolate, use 240g dark chocolate and 240g (1 cup) of heavy cream.

Milk chocolate creates a sweeter, fudgier filling, while dark chocolate makes the cake richer and less sweet.

Why is my chocolate ganache too runny?

The most likely reason is that it’s still too warm. Ganache thickens significantly as it cools. Let it sit at room temperature longer, or chill it briefly and stir as needed until it reaches a spreadable consistency.

It’s also important to use good quality chocolate. Sometimes brands of cheaper chocolate can include additives that affect the way it melts and sets.

How do I keep the cake layers from sliding?

Make sure the chocolate ganache is fully cooled and thick before assembling the cake. Don’t overfill the layers, and use chilled cake layers if possible.

Once the cake is stacked, chill it for about 15 minutes in the freezer or 30 minutes in the fridge before frosting. This gives the fillings time to firm up and helps everything stay in place.

Why is my ganache too thick?

If your ganache is too thick, it may have cooled for too long or been chilled too much. Let it sit at room temperature until it softens to a spreadable consistency.

If it’s still too firm, microwave it in 5- to 10-second intervals, stirring between each, until it loosens up. But be careful not to overheat it, or the emulsion can break, and the ganache will lose its smooth consistency.

Can I use Oreo crumbs instead of chopped Oreos?

Yes, you can use Oreo crumbs instead of chopped Oreos in the buttercream, but the texture will be a little different. Finely chopped Oreos give the filling more cookies-and-cream texture, while Oreo crumbs blend more fully into the frosting and will give it a grey color.

If you use crumbs, I recommend using 3/4 cup of finely crushed Oreos. You may also need to add a bit more heavy cream to get the texture right.

Tips for Making the Best Oreo Fudge Cake

• Properly measure the flour. Spoon it into your measuring cup and level it with a knife, or use a kitchen scale for the most accurate results.
• Use room-temperature ingredients when called for. They mix together more easily and help create smoother batters, ganache, and frosting.
• Chill the stacked cake before frosting. With both ganache and buttercream between the layers, this extra step makes the cake much easier to finish.
• If your cake layers turn out less than perfect, check out my cake troubleshooting guide to figure out what might have happened.

Let Me Know What You Think!

If you make this Oreo fudge cake recipe, I’d love to hear what you think! Let me know by leaving a rating and comment below.

And don’t forget to tag me @chelsweets and use #chelsweets if you share on social media so I can see your amazing creations.

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