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Dark Chocolate Mousse Cake with a Chocolate Ganache Frosting
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This homemade Dark Chocolate Mousse Cake is rich, fluffy, and totally over the top with layers of moist chocolate cake, whipped mousse, and a glossy ganache that drips down the sides beautifully. It’s the kind of dessert that looks like it came straight from a fancy bakery and is the BEST cake to make for any occasion!
There are certain times of the year where it’s totally justified to have a really indulgent meal (think Oven Fried Chicken or Italian Stuffed Shells). But if you’re starting with a meal like that then you MUST have an equally indulgent dessert! That’s where this creamy, sweet, rich mousse cake made with dark chocolate comes in.
The idea for this cake came from a trip to Disney World where we had dinner inside the Beauty and the Beast castle. The whole meal was incredible, but the part I still think about is the chocolate mousse cake we had at the end. It was shaped like Mickey and hands down one of the best chocolate desserts I’ve ever tasted. I wanted to recreate that same magical, chocolate-filled cake at home but in a simple layer cake version that anyone can make and I’m so happy to say I nailed it!
Each part of this cake is something special. The cake itself stays moist and soft thanks to sour cream and buttermilk, which add just the right texture and flavor. The mousse is light and creamy from whipped heavy cream mixed with melted chocolate that adds just enough richness without being too heavy. And that ganache on top is pure heaven. It’s simple to make but makes a big impact and brings everything together.
This is the kind of dessert that looks like it came straight from a fancy bakery display and honestly, you’ll have a hard time convincing people that YOU made it. We make it for birthdays, parties, or any holiday where you want to bring a comforting chocolatey indulgence!
Ingredients You’ll Need
All-Purpose Flour – This gives the cake its structure and helps everything hold together nicely. Make sure you scoop and level so you don’t accidentally pack in too much and end up with a dry cake as you want everything in this cake to be moist.
Unsweetened Cocoa Powder – Brings all that rich, chocolatey flavor. Use a good-quality cocoa powder here because it really sets the tone for the entire cake.
White Sugar – Sweetens things up and keeps the cake soft and moist. It’s not just about sweetness, it helps with texture too.
Baking Soda and Baking Powder – The ingredients that make the cake rise and stay fluffy. You need both here for the perfect lift and crumb.
Kosher Salt – A small amount that makes a big difference. It brings out the chocolate flavor and balances the sweetness.
Espresso Powder – It deepens the chocolate flavor without making it taste like coffee. Trust me, once you try it, you’ll add it to every chocolate cake.
Vegetable Oil – Keeps the cake super moist and tender. It’s why this cake stays soft even after being in the fridge.
Eggs – Help everything bind together and give the cake structure. Room temp is best so they mix in smoothly.
Sour Cream – Adds moisture and a little tang that makes the cake taste rich and not overly sweet. It’s one of my favorite baking ingredients.
Buttermilk – Lightens up the batter and keeps the texture soft and airy. It also gives the cake that slight tang that pairs perfectly with dark chocolate.
Vanilla Extract – Rounds out all the flavors and adds a cozy, familiar flavor.
Hot Coffee – Enhances the cocoa and makes the batter silky smooth. You won’t taste the coffee, but the chocolate flavor will be next level.
Semi-Sweet Chocolate Chips – Fold these in at the end for extra chocolate flavor.
Hot Water – Helps “bloom” the cocoa in the mousse so it blends evenly with the chocolate.
Semisweet Chocolate Bars – These are melted into the mousse to make it rich and velvety. Go for bars over chips, they melt smoother.
Heavy Cream – Whip it for fluffy mousse, warm it for silky ganache, it does it all!
Powdered Sugar – Adds a touch of sweetness to the mousse without weighing it down. It also helps the whipped cream hold its shape.
Semisweet Chocolate Chunks – Used for the ganache topping. Once melted with cream, you’ll get that dreamy, glossy drip that makes this cake look bakery-level.
Step By Step Instructions
Prepare for baking: Preheat the oven to 350°F and spray three 8-inch round cake pans with nonstick baking spray. Line the bottoms with parchment paper, then lightly spray again.
Mix the dry ingredients: In a large mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, white sugar, baking soda, baking powder, kosher salt, and espresso powder. Set this dry mixture aside while you prepare the wet ingredients.
Combine the wet ingredients: In the bowl of a stand mixer (or using a handheld mixer), mix the vegetable oil, eggs, sour cream, buttermilk, and vanilla extract on medium speed until the mixture is smooth and creamy.
Bring the batter together: With the mixer on low speed, gradually add the dry ingredient mixture to the wet ingredients in small batches. Mix just until everything is combined and don’t overmix.
Add hot coffee and chocolate chips: Slowly pour in the hot coffee and mix on low speed until the batter is fully smooth and silky. Use a spatula to gently fold in the semi-sweet chocolate chips for extra richness.
Bake the chocolate cake layers: Evenly divide the cake batter between the three prepared cake pans. Bake for 20 to 25 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
Make the Chocolate Mousse Filling
Bloom the cocoa powder: In a medium bowl, whisk the hot water and unsweetened cocoa powder together until smooth.
Melt the chocolate: In a microwave-safe bowl, heat the chopped semisweet chocolate bars in 30-second increments, stirring in between, until smooth and fully melted. Pour the melted chocolate into the cocoa mixture and stir until combined. Set aside to cool slightly.
Whip the cream: In a large bowl or stand mixer, whip the heavy cream with powdered sugar and vanilla extract until medium peaks form.
Fold mousse together: Gently fold the chocolate mixture into the whipped cream using a spatula. Be careful not to overmix. Stop once it’s smooth and well blended. Cover and refrigerate the mousse for at least 2 hours so it firms up for layering.
Assemble the Cake
Level the cake layers: Once the cake layers are fully cooled, use a serrated knife to level the tops. You can also slice each cake in half horizontally if you want more layers.
Layer the mousse: Place one cake layer on a cake stand or serving plate. Spread a generous layer of chocolate mousse on top using an offset spatula. Repeat the process with the remaining layers, finishing with a layer of mousse on the top. You can use any extra mousse to create a “naked cake” look by smoothing it around the sides.
Chill the cake: Place the assembled cake in the fridge for 30 minutes to firm up before adding the ganache topping.
Make the Chocolate Ganache
Prepare the chocolate: Place the semisweet chocolate chunks in a medium bowl and set aside.
Heat the cream: In a small saucepan or microwave-safe container, heat the heavy cream until steaming but not boiling.
Combine to make ganache: Pour the hot cream over the chocolate chunks and let it sit undisturbed for 3 minutes. After that, gently stir the mixture until it becomes smooth, glossy, and fully melted. Let the ganache cool for about 15 minutes so it thickens slightly for perfect drips.
Finish and Serve
Top the cake: Pour the chocolate ganache over the top of the chilled mousse cake, allowing it to naturally drip down the sides. Use a spoon or offset spatula to guide the ganache if needed.
Chill or serve: You can serve the cake right away or refrigerate it until ready to enjoy. This dark chocolate mousse cake tastes amazing chilled or at room temperature.
Expert Tips
Room temperature ingredients mix better. Let your eggs, sour cream, and buttermilk sit out for a bit before baking so the batter comes together smoother and bakes more evenly.
Whisk the dry ingredients thoroughly. This helps evenly distribute the leaveners and cocoa powder so you don’t end up with pockets of bitter or flat bites in the cake.
Use a kitchen scale if you have one. Weighing your flour and cocoa powder gives you way more accurate results and keeps the cake from turning out dry or dense.
Let the chocolate cool slightly before adding it to the whipped cream. If it’s too warm, it can deflate the mousse or create streaks.
Don’t skip chilling the mousse. It needs time to set up so it doesn’t squish out between the layers when you stack the cake.
Cut your cake layers with a serrated knife using a gentle sawing motion. Pressing down can tear the cake, but a light touch keeps the layers clean and pretty.
Refrigerate the cake before adding ganache. A cold surface helps the ganache set quickly and drip beautifully instead of running off the edges.
Use a squeeze bottle or spoon to control the ganache drips. This gives you more control and helps you create that picture-perfect bakery look.
Chill the mixing bowl and beaters before whipping the cream. Cold tools help the cream whip up faster and hold those fluffy peaks longer.
Ways To Customize
Swap the semisweet chocolate for dark chocolate in the ganache for a less sweet finish.
Add a layer of fresh raspberries or sliced strawberries between the cake and mousse for a fruity contrast.
Replace the espresso powder with instant coffee granules if that’s what you have on hand as they work just as well to deepen the chocolate flavor.
Stir a splash of liqueur like Kahlúa or Baileys into the ganache or mousse for a grown-up twist.
Add a layer of crushed chocolate cookies or Oreos between the mousse and cake layers for a cookie crunch.
Swap the cocoa powder in the mousse for melted white chocolate to create a contrasting layer of flavor and color.
Fold a spoonful of peanut butter into the mousse for a chocolate-peanut butter combo.
Top the finished cake with chocolate curls, sprinkles, or edible gold leaf to level up the presentation for a party or holiday dessert.
Storing and Serving Instructions
You can store the cake in the refrigerator for up to 4–5 days. Just cover it loosely with plastic wrap or place it in a cake container to keep it from drying out. Since the mousse contains whipped cream, it’s important to keep the cake chilled when you’re not serving it. For the best texture and flavor, let slices sit at room temperature for about 15–20 minutes before serving so the mousse softens up just slightly.
If you’re making the cake in advance, you can bake the cake layers a day ahead and store them tightly wrapped at room temperature. The mousse and ganache should be prepared fresh and used the day you assemble the cake for the best texture. Once the full cake is assembled, refrigerate it until serving.
Freezing this cake isn’t recommended once it’s fully assembled, as the mousse can lose its airy texture and separate when thawed. However, you can freeze the baked cake layers on their own. Wrap each layer tightly in plastic wrap and then foil, and freeze for up to two months. Let them thaw in the fridge overnight before assembling.
FAQ
Can I use two cake pans instead of three?
Yes, you can use two 9-inch pans instead of three 8-inch ones, but the bake time will be slightly longer, about 25 to 30 minutes. Just keep an eye on the center and use a toothpick to check for doneness.
What’s the best way to transport this cake without ruining the ganache drip?
Chill the fully assembled cake until the ganache is set, then place it in a tall cake carrier or box. If you’re traveling a longer distance, pop it in the freezer for 30–45 minutes beforehand to firm it up, just don’t let it freeze completely.
Why is my ganache too runny or too thick?
If your ganache is too runny, the cream was probably too hot or the ratio of cream to chocolate was off. If it’s too thick, let it sit at room temperature for a few more minutes or gently reheat it in 5-second microwave bursts until it loosens up.
Do I need a stand mixer for this recipe?
Nope! A hand mixer works just fine for both the cake and mousse. Just make sure to use a large bowl when whipping the cream, it fluffs up fast and can splatter if the bowl is too small.
How do I fix a mousse that looks grainy or curdled?
This usually happens if the melted chocolate was too hot when added to the whipped cream. You can gently fold in a bit of cold whipped cream to smooth it out, but if it’s too far gone, it’s best to start over with properly cooled chocolate.
What type of cocoa powder works best, Dutch-processed or natural?
This recipe works best with unsweetened natural cocoa powder because it reacts with the baking soda for proper lift. Dutch-processed cocoa will make the cake darker but may not rise as well unless you adjust the leaveners.
More Chocolate Dessert Recipes
Baked Chocolate Donuts
Dark Chocolate Brownie Bites
Homemade Chocolate Fudge with Marshmallow Fluff
Print
Dark Chocolate Mousse Cake with Chocolate Ganache Frosting
Layers of rich dark chocolate cake with light chocolate mousse in between, topped with a decadent chocolate ganache frosting. Over the top and incredible!
Ingredients
Cake-
1 ¾ cups all-purpose flour
¾ cup unsweetened cocoa powder
1 ¾ cups white sugar
2 teaspoons baking soda
1 teaspoon baking powder
1 teaspoon kosher salt
2 teaspoons espresso powder
½ cup vegetable oil
2 large eggs
¾ cup Hiland Dairy Sour Cream
½ cup Hiland Dairy Buttermilk
2 teaspoons pure vanilla extract
½ cup hot coffee
1 cup semi-sweet chocolate chips
Mousse-
½ cup hot water
¼ cup unsweetened cocoa powder
2 (4 ounce) semisweet chocolate bars, chopped
2 cups Hiland Dairy Heavy Cream
2 Tablespoons Powdered Sugar
½ teaspoon pure vanilla extract
Chocolate Ganache-
1/2 cup semisweet chocolate chunks (4 ounces) , chopped
1/2 cup Hiland Dairy Heavy Cream
Instructions
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Preheat the oven to 350 degrees. Spray three 8 inch cake pans with nonstick spray and then line with parchment and spray again. (totally worth the extra effort)
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Cake: In a large bowl, add the flour, cocoa powder, sugar, baking powder, baking soda, salt, and espresso powder and whisk together. Set aside.
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In a stand mixer on low to medium speed, mix the oil, eggs, Hiland Dairy Sour Cream, Buttermilk, and vanilla until smooth.
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Add the dry ingredients a little bit at a time, and mix on low after each addition until all combined. Slowly add the hot coffee and mix on low until smooth. Fold in the chocolate chips by hand.
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Pour the batter into each pan evenly between the three pans. Bake for 20-25 minutes or until a toothpick inserted in the middle comes out clean. Set aside to cool completely.
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Mousse: In a medium bowl, whisk together the hot water and cocoa powder. Set aside.
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In a microwave safe bowl, add the chopped chocolate and microwave in 30 second increments until smooth and melted. Pour the melted chocolate into the cocoa/water mix and stir together until combined.
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Using a handheld or stand mixer, whisk together the Hiland heavy cream, powdered sugar, and vanilla extract together until medium peaks form. About 3 minutes of mixing.
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Pour the chocolate mixture into the whipped cream mixture and fold together until combined and smooth. Careful not to over mix. Cover and refrigerate for at least 2 hours.
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Cake assembly: Use a serrated knife to cut cakes in half if you want several layers or just cut tops off of each cake to level them out. Place the bottom layer on a cake board or stand. Scoop chocolate mousse on the layer and spread out evenly. Top with the next layer and repeat with the mousse and the remaining layers. Use an offset spatula to spread the mousse around the sides of the cake too to create a crumb coat or a naked cake look. Refrigerate until ready to do the chocolate ganache layer.
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Ganache: In a medium bowl, add the chopped chocolate pieces. Set aside. Heat the Hiland Heavy Cream in the microwave or on the stovetop until hot but not boiling. Pour the heavy cream over the chocolate pieces. Do not stir. Let it sit for 3 minutes and do not touch.
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After 3 minutes, stir the chocolate and heavy cream together until smooth and all combined. Let sit for 15 minutes and then pour chocolate ganache over the top of the cake and let it drizzle over the edges.
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Serve immediately or later. Tastes amazing chilled or at room temperature.
Notes
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2 Responses
This was one of the best cakes I ever made! I’ll make this recipe for the rest of my life!
Thank you!! I’m so glad you love it! I love this cake so much too!