Chocolate Graham Cracker Cake with Creamy Chocolate Mousse Filling
Avery dreamed up this cake for her birthday, and let me tell you—she nailed it. Every layer, every element was her idea: rich dark chocolate cake layers, graham cracker clusters, silky graham cracker buttercream, light chocolate mousse, and glossy chocolate ganache.
Sounds heavenly, right? Honestly, it reminds me of a chocolate-covered graham cracker—but even better.
How to Make Rich and Moist Chocolate Cake Layers
For the base of this cake, I use my go-to chocolate cake recipe, made with high-quality cocoa like Cacao Barry Extra Brute. It’s rich, soft, and bakes beautifully every time. I baked the batter in two 8-inch round cake pans for thicker layers that I could split later to make four thinner layers (helps maximize fillings!). You’ll wait until the layers are cooled completely before you torte each cake (slice in half horizontally) to create 4 even, thin layers.
Make-ahead tip: You can bake the cake layers in advance. Just wrap them in plastic wrap and store in the freezer. When you’re ready to use, let them thaw at room temperature for about 30 minutes before assembling.
Easy Chocolate Mousse Filling
This mousse might surprise you—no eggs, no cooking, and no stove required. It whips up in under 5 minutes with a hand mixer. All you need is:
- Heavy whipping cream
- Cocoa powder
- Powdered sugar
- Vanilla extract
Just be careful not to overmix. You’re aiming for medium-soft peaks for a creamy, dreamy texture that spreads easily between layers.
Graham Cracker Buttercream (The Silky Smooth Version)
When Avery described her dream cake, I immediately thought of the graham cracker buttercream from my Graham Slam Cake. But this time, I wanted to level it up—smoother, silkier, and more flavorful.
I took inspiration from Christina Tosi’s milk soaks, but with a twist. I soaked graham cracker crumbs in heavy cream (not milk), hoping to drain and use the flavored liquid. But the mixture turned into a paste instead of a soak. Hmmm…
I decided to roll with it. I added the graham cracker paste straight into the butter and whipped it up before adding powdered sugar, cinnamon, vanilla, and salt. What happened next? Magic. The result was a super smooth, rich buttercream that reminded me of Swiss meringue in texture but with way less work.
Graham Cracker Clusters
For texture and flavor, we’re making crunchy graham cracker clusters using graham cracker crumbs, flour, brown sugar, and butter. These create cookie-like bits that hold their crunch between the soft mousse and cake layers.
I like to add these clusters between every layer and even sprinkle some on top of the finished cake. Don’t be shy—you can be generous here. We also added extra crumbs to each slice as we served it. So good!
Want even more graham flavor? If you want to maximize the graham cracker flavor and texture, you can follow the steps for the crust and cake in my S’mores Cake, where you’ll bake the cake layers right on top of the graham cracker layer.
Complement your kitchen with my baking tools ⤵
This cake turned out to be one of the best birthday cakes we’ve made. Avery gave it a 10/10, and I can’t wait for you to try it. Whether you’re baking for a birthday or just craving something chocolatey and nostalgic, this cake is guaranteed to impress.
FOR THE CAKE
- 2 cups (240 g) all-purpose flour
- 1 3/4 cups (350 g) granulated sugar
- 3/4 cups (88.5 g0 dark cocoa powder
- 2 teaspoons (8 g) baking soda
- 3/4 teaspoon (3 g) baking powder
- 1 teaspoon (6 g0 salt
- 1 cup (240 g) buttermilk, at room temperature
- 1 cup (236.6 g) hot water or coffee
- 1/2 cup (109 g) vegetable oil
- 3 large eggs, at room temperature
- 1 teaspoon (4.2 g) pure vanilla extract
FOR THE GRAHAM CRACKER CLUSTERS
- 1 1/2 cup (180 g) graham cracker crumbs, about 13 full graham crackers
- 1/2 cup (60 g) all-purpose flour
- 1/2 cup (113 g) unsalted butter, melted
- 1/3 cup (73 g) brown sugar
FOR THE CHOCOLATE MOUSSE
- 1 1/4 cup (288 g) heavy whipping cream
- 1/4 cup (30 g) cocoa powder
- 1/3 cup (42 g) powdered sugar
- 1/2 (2.3 g) teaspoon vanilla extract
FOR THE GRAHAM CRACKER BUTTERCREAM
- 1/2 cup (60 g) finely ground graham crackers, about 5 full graham crackers
- 1/2 cup (115.5 g) heavy whipping cream
- 2 cups (452 g) unsalted butter slightly cold
- 5 1/2 cups (687.5 g) powdered sugar measured and then sifted
- 1 teaspoon (2.6 g) cinnamon
- 1 teaspoon (4.6 g) vanilla extract
- Pinch of salt
For the Ganache/The Drip
- 1/2 cup (90 g) semi-sweet or dark chocolate chips
- 1/2 cup (115.5 g) heavy whipping cream (I use 40% fat, so if you use a lower fat cream, you may want to only use 1/4-1/3 cup cream)
FOR THE CAKE
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Preheat the oven to 325 degrees F. Spray two 8-inch round cake pans with non-stick spray, line with parchment paper, and spray again. Set aside.
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Combine the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.
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In another bowl, whisk together the buttermilk, water (or coffee), oil, eggs, and vanilla.
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With the mixer on low speed, slowly add the wet ingredients to the dry, scraping the bottom of the bowl with a rubber spatula.
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Divide the batter between the two pans and bake for 30 to 35 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumbs on it.
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Cool in the pans for 10 minutes, then turn them out onto a cooling rack and cool completely.
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Torte each cake layer, dividing it in half horizontally. Wrap each cake (the two thin layers for each cake can be wrapped together) and freeze until ready to use.
For the Graham Cracker Clusters
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Preheat the oven to 325°F. Line a cookie sheet with parchment paper. Set aside.
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Combine the graham cracker crumbs, brown sugar and flour in a medium-size mixing bowl. Whisk to combine.
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Stir in the melted butter, making sure all the crumbs get coated and form clusters.
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Spread the clusters on the prepared sheet pan. Bake for 7 minutes and then toss the crumbs a bit and bake for another 7 minutes.
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Allow the clusters to cool completely on the pan before using. The clusters can be stored in an airtight container at room temperature for 1 week, or in the refrigerator or freezer for up to 1 month.
For the Chocolate Mousse
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In a medium size mixing bowl (ideally a chilled stainless steel bowl), combine the ingredients. Beat on high speed until medium-stiff peaks form.
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Store in an airtight container in the fridge until ready to use. Can be made a day ahead.
FOR THE GRAHAM CRACKER BUTTERCREAM
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In a small mixing bowl, combine the crumbs with the heavy cream. Stir to combine. Allow to rest for about 10 to 20 minutes. The mixture should be thick, like a paste. You can use this right away or store in the fridge until ready to make the rest of the buttercream.
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In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium-high speed until light and fluffy, about 2 minutes.
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Add the graham cracker paste and continue to mix on medium-high for another minute or two. The mixture should be smooth and silky.
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With the mixer on low speed, gradually add the powdered sugar, followed by the cinnamon, vanilla and salt. Make sure to scrape down the sides and bottom of the bowl.
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Turn the mixer to medium-high speed and beat the buttercream for an additional 3 to 5 minutes. The buttercream should be lighter in color and fluffy and smooth in texture.
For the Ganache
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In a microwave save bowl, combine the chocolate chips and the heavy whipping cream. Heat for about 30 seconds and then stir. Continue to heat in 30 second increments until the chocolate is melted and smooth.
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The mixture should be thin enough to drip around the top of the cake. If it’s too thick, add a few more tablespoons of warm heavy cream. If it’s too thin, add more chocolate chips.
Assembly
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On a cake board or cake stand, place the first layer of cake (this should be one of the bottom pieces of the torted cake). Pipe a rim of buttercream around the top edge of the cake.
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Evenly spread half of the chocolate mousse filling on the cake layer, Top generously with an even layer of graham cracker clusters, gently patting them in place.
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Place the next cake layer (this will be the top half of the cake) on the filling. Evenly spread about 1 cup of buttercream over the cake. Again, generously top with an even layer of clusters, gently patting into place.
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Place the third cake layer (this should be the top half of the second cake layer) on the filling.
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Pipe a rim of buttercream around the top edge of the cake. Fill with the second half of the mousse and again top with clusters.
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Place the final cake layer (the bottom half of the second cake layer) on the filling (bottom side up).
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Evenly spread a thin layer of buttercream around the entire cake to create the crumb coat. Freeze the cake for 15 minutes.
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Continue to frost the cake with the remaining buttercream and apply the drip.
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