This chocolate mousse cake is a chocolate lover’s DREAM. It’s three exquisite layers of chocolate in one beautiful and easy dessert: a rich and decadent chocolate cake with a generous layer of velvety chocolate mousse on top, topped with shiny chocolate ganache. I love garnishing this dessert with fresh raspberries and chocolate covered espresso beans for a little sophistication. She looks complex, but this is probably one of the easiest chocolate mousse cakes you’ll ever make. I can’t wait to show you how!
One reader, Lauren, says: “This recipe is phenomenal!! I made this for my family for Valentine’s Day and it was soo decadent. Everyone kept saying how moist the cake was and how smooth the mousse was. It was officially named our yearly Valentine dessert!” ★★★★★
Decadent Chocolate Cake
This rich and decadent chocolate cake layer is a halved version of my favorite one-bowl chocolate cake. There are so many reasons why I gravitate towards this recipe any time I need a chocolate cake: It’s nearly as easy as whipping up a boxed cake mix and uses simple ingredients I always have in my pantry. The crumb is stick-to-your-fork moist due to the vegetable oil base and the addition of buttermilk. It has an incredible chocolate flavor that’s even more amplified with a little bit of coffee. There are absolutely no complicated steps involved, which makes it absolutely fail proof. I could go on forever!
You’ll bake the chocolate cake layer in a 9-inch springform pan – the same pan that you’ll be assembling the rest of the cake components in. Once baked, there are two important things to do before moving on to the mousse portion of the recipe:
- Make sure the chocolate cake is fully cooled to room temperature before adding the mousse layer on top.
- After the cake has cooled, level it so that you have a nice even cake layer for the mousse to sit on. Trimming off the top also makes the cake more porous, which helps the mousse soak into the cake slightly and make it even more moist.
The Easiest Chocolate Mousse
This may not be a traditional chocolate mousse recipe, but it tastes just as delicious and pillowy soft without any eggs or complicated cooking techniques. Instead, this mousse starts with a classic chocolate ganache recipe that is two parts chocolate and one part heavy whipping cream. In other words, 2 Cups of semi-sweet chocolate chips + 1 Cup of heavy whipping cream. You’ll bring the cream to a simmer in a saucepan, then pour it over the chocolate chips and whisk until the consistency is uniform, then let the ganache cool to room temperature.
The second part of the chocolate mousse is making the whipped cream. This essentially means blending together more heavy whipping cream, a little powdered sugar, some vanilla, and some instant coffee or espresso powder (optional, but delicious!). You’ll whip these ingredients together until stiff peaks form, then fold the whipped cream into the ganache until you have a creamy chocolate mousse. It’s so good I could eat it by the spoonful!
Assembling the Chocolate Mousse Cake
Now that you have your cake and mousse components, you’ll assemble them in the springform pan. You’ll wrap an acetate collar around the cake layer before adding the mousse on top and smoothing it down with an angled spatula. Then, place the whole thing in the refrigerator until it sets. This takes about 5-6 hours, but I like to assemble the chocolate mousse cake the night before I’m serving it just so I know I’m not cutting it too close.
After the mousse cake is set it’s so satisfying to unwrap the acetate collar and see the layers!
Chocolate Ganache + Finishing Touches
The last chocolate component of this mousse cake is the chocolate ganache topping. It’s made exactly the same way you make the chocolate ganache for the mousse base, only this time we use a 1:1 ratio of chocolate to heavy whipping cream (aka ½ Cup semi-sweet chocolate chips + ½ Cup heavy whipping cream). This makes the ganache perfect pouring consistency.
Once you make the chocolate ganache, it takes about 20 minutes for it to cool to room temperature before you can pour it on top of the chocolate mousse cake, which at this point should be fully set. I remove the springform collar from the pan to expose the beautiful mousse cake layers, then pour the ganache on top and spread it with an angled icing spatula until it drips over the sides.
You can totally leave this chocolate mousse cake as-is and let those three beautiful layers of chocolate shine. I like to garnish the cake with fresh raspberries and chocolate covered espresso beans for a little extra pop of color and texture. It’s so pretty in a crescent shape, but feel free to get creative with how you decorate (or don’t decorate)!
Chocolate Mousse Cake Tips for Success
The different components of this chocolate mousse cake are each easy to make, but there are a few things to keep in mind as you navigate this recipe:
- Plan it out. There’s a fair amount of waiting in this recipe, which requires some planning. You’ll need to wait for the cake layer to come to room temperature, wait for the ganache base for the mousse to come to room temperature, wait for the entire mousse cake to set, then wait for the ganache topping to come to room temperature before adding the finishing touches. I recommend reading through the recipe and planning out the elements over the course of a couple days so you don’t feel rushed.
- Make your springform pan leak-proof. Since you’ll be baking the chocolate cake layer in the springform pan, it’s important to make sure it’s leak-proof. Otherwise the batter might leak out in the baking process which is frustrating and messy. If you have a leaky springform pan, one trick is to line the outside with aluminum foil (in addition to lining the inside with parchment). This will catch any batter that tries to escape.
- Level the chocolate cake layer. This isn’t a requirement, but it does make the final slice a little more aesthetically pleasing because all the layers will be so even. Also, it makes the cake layer more porous for the mousse to soak in a little, which makes it even more moist.
- Let the mousse cake set. In order for the chocolate mousse cake to demold perfectly, it’s important to wait at least 6 hours for it to set. This way it won’t budge when you remove the springform collar.
- Let the ganache topping cool. The ganache topping will thicken slightly as it cools, making it perfect for pouring over the mousse cake and gently dripping down the sides. This post has everything you need to know about topping a cake with ganache and it’s worth a read if you haven’t worked with ganache before.
I’m so excited for you to make this chocolate mousse cake! Being a devoted chocolate lover myself, I think it’s one of the best desserts I’ve ever made. I hope you love it as much as I do!
Easy Chocolate Mousse Cake
Equipment
Ingredients
Chocolate Cake
- 1 Cup (133g) all purpose flour
- 3/4 Cup (150g) granulated sugar
- 1/3 Cup (30g) unsweetened natural cocoa powder
- 1 tsp baking soda
- 1/2 tsp baking powder
- 1/4 tsp salt
- 1/4 Cup (60ml) vegetable oil
- 1 large egg, room temperature
- 1 tsp pure vanilla extract
- 1/2 Cup (120ml) full-fat buttermilk*, room temperature DIY recipe in notes
- 1/2 Cup (120ml) hot coffee or hot water
Easy Chocolate Mousse
- 2 Cups (370g) semi-sweet chocolate chips
- 2 1/3 Cups (560ml) heavy whipping cream, divided
- 2 Tbsp powdered sugar
- 2 tsp pure vanilla extract
- 1 tsp instant coffee or espresso powder (optional)
Chocolate Ganache
- 1/2 Cup (93g) semi-sweet chocolate chips
- 1/2 Cup (120ml) heavy whipping cream
Garnishes (optional)
- 3 Oz fresh raspberries
- 2 Oz chocolate covered espresso beans
Instructions
Make the Chocolate Cake
- Preheat the oven to 350ºF (177ºC) and prepare a 9-inch springform pan by spraying the sides with cooking spray and fitting the bottom with a parchment circle. I also like to line the outside of the pan with aluminum foil to ensure there is no leakage of cake batter, but if you're sure your springform pan is leak-proof you can skip the aluminum foil.
- Place all of the dry ingredients into a large bowl and whisk to combine. Add the vegetable oil, eggs, vanilla, and buttermilk and whisk until uniform. Add the hot coffee (or hot water) in a slow stream, then whisk until smooth and combined. The batter will be very thin.
- Pour into the prepared cake pan and bake for 25-30 minutes, until a toothpick inserted comes out clean. Cool completely before moving on to making the chocolate mousse.
Make the Easy Chocolate Mousse
- Place the semi-sweet chocolate chips into a large glass or metal bowl and set aside.
- Place 1 Cup (240ml) of the heavy whipping cream into a small saucepan set over medium-low heat. Whisk frequently until the cream begins to simmer around the edges, then pour it over the chocolate chips and whisk until it becomes a smooth ganache. Set aside until the ganache cools to room temperature, about 25 minutes. Wait until it is room temperature to move on to the next step.
- In the bowl of your stand mixer fitted with the whisk attachment (or using a medium bowl and hand mixer), add the remaining 1 1/3 Cups (320ml) of heavy whipping cream, powdered sugar, vanilla, and instant coffee or espresso powder (if using). Mix at low speed until the ingredients are combined, then turn the mixer to high and beat until stiff peaks form, about 4 minutes.
- Add the whipped cream mixture to the cooled ganache and fold gently with a rubber spatula until there are no streaks.
Assemble the Chocolate Mousse Cake
- Remove the cooled chocolate cake layer from the springform pan. Using a serrated knife or cake leveler, level the top of the cake to create an even layer. Gently peel off the parchment paper on the bottom of the cake layer, then place it back into the springform pan.
- Wrap an acetate cake collar around the cake layer and secure it with a piece of scotch tape. This will help keep the mousse in place as it sets.
- Add the chocolate mousse on top of the cake layer and smooth it down with an angled spatula until it reaches the edges of the acetate and has an even surface. Refrigerate for 6 hours, or overnight.
Make the Chocolate Ganache
- Wait until the chocolate mousse cake is set before making the chocolate ganache unless you're making it ahead of time (instructions for making ahead and reheating are in the notes section of this recipe).
- Place 1/2 Cup (93g) of semi-sweet chocolate chips into a medium glass or metal bowl and set aside.
- Add 1/2 Cup (120ml) of heavy whipping cream into a small saucepan set over medium heat. Bring to a simmer, whisking frequently, then pour it over the bowl of chocolate and whisk until uniform and smooth. Allow the chocolate ganache to cool to room temperature, about 20 minutes.
Add the Finishing Touches
- Once the mousse cake is set, unclip the springform collar and remove it. Then, unwrap the acetate from the sides of the mousse cake.
- Pour the cooled chocolate ganache over the top of the cold chocolate mousse cake and spread it with an angled spatula until it runs over the edges. To create the look pictured, garnish with fresh raspberries and chocolate covered espresso beans in a crescent design. Serve immediately, or place back into the refrigerator until you're ready to serve.
Notes
- The chocolate cake layer can be made ahead and stored at room temperature, covered tightly in plastic wrap, for up to two days. Alternatively, you can cover with plastic wrap and store in the freezer for up to two months before thawing to room temperature.
- The chocolate ganache can be made ahead and stored in the refrigerator in an airtight container for up to two weeks. When you’re ready to use it as a drip, microwave it in 10 second increments, stirring after every interval until your ganache is room temperature and uniform in consistency.
- The assembled chocolate mousse cake can be stored in the refrigerator in its springform pan, the top covered with plastic wrap or aluminum foil, for up to five days.
Best Recipe ever. I have made it twice and the gusts have fallen in love both times!!
Yay, Unzal! I’m so happy to hear that 🙂
Love this — your “three-chocolate-layers-in-one” cake made me want to high-five my dessert plate ! The mix of moist cake, pillowy mousse and shiny ganache looks temptingly decadent yet surprisingly doable. I’m totally bookmarking this for when I need to impress *and* not stress. Thanks for making chocolate feel this fun and fancy without the drama!
Yay, Brooke! So happy you love this one as much as I do!
Hi Whitney,
Thank you for this recipe. I am planning to create a mouse cake layer for a birthday cake. Do you think It will hold well if I frost it with American buttercream? Thank you
What size acetate collar you use? Thank you.
Hi Jackie! Just enough to cover the sides of the pan, so about 3 inches. You can also use parchment or wax paper strips to keep the mousse from sticking to the sides. Hope that helps!
OMG! I made this today and it turned out fabulous! I made a few alterations, from using 1/3 cup of sugar and 1/3 cup of maple syrup, adding 2 TBSP of greek yogurt and 1/2 tsp of white vinegar and a tsp of instant Coffee powder not mixed with water.
For the mousse I only used 1 1/2 cup of heavy whipping cream to 6oz of chocolate, which in my opinion was alot! Yet it worked out great since I split the cake into two layers, but if it was one layer then cutting that amount in half would work out great for me too.
Just made this for my birthday and it turned out beautiful and delicious!!
Definitely going in my favorites. I didn’t have buttermilk or whole milk so I used a mixture of 2% and heavy cream with lemon juice and it worked fine.
Yay, Rachel! That makes me so happy! And great to know that it worked with the heavy cream/lemon juice mixture. Happy belated birthday!
This cake was delicious!! So simple to make and so decadent!!!!
Yay, Savia! So happy you loved this one 🙂
Wow was this easy and absolutely delicious and beautiful!!!
Yay, Silvia! I’m so happy to hear that 🙂
Hi! It will be my first time making it and I’m worried the mousse won’t keep firm. I’ve seen other recipes that add gelatin. Does the mousse become really firm? Would you suggest adding gelatin?
Hi Mari! The mousse does become very firm in this recipe, it’s not a traditional mousse which involves aerated eggs. Since the whipped cream stabilizes this mousse perfectly, there’s no need to add gelatin.
Do you think the mousse would work with chopped dark chocolate ~70%? I don’t have any semisweet chocolate chips right now but I have a bunch of dark chocolate bars to use up… Thank you in advance!
Hi Mandy! It will definitely work with dark chocolate. Enjoy!
This is probably the best dessert I ever made! This is restaurant quality. It was a big hit! Thank you for sharing this recipe. I’m sure I will be making this many times.
I’m so happy to hear that!! Thanks for letting me know it was a hit 🙂
Can I substitute anything for the vegetable oil?
Hi Ashley! Any neutral flavored oil will work just fine.
This recipe is phenomenal!! I made this for my family for Valentine’s Day and it was soo decadent. Everyone kept saying how moist the cake was and how smooth the mousse was. It was officially named our yearly Valentine dessert!
Yay, Lauren!! I’m so happy this recipe was such a hit and you want to make it a tradition 🙂 there’s no greater compliment!
Hi…can I substitute almond flour.
Hi there! I’ve never tried this recipe with almond flour so it would be an experiment. Let me know if you try it!
Le meilleur gateau mousse que j’ai faite pour l’anniversaire de mon garçon.Les invites se sont regales Merci
That’s amazing, Danielle! I’m so happy to hear it was a hit!
Hi there,
On this Easy Chocolate Mousse Cake, can I use milk and not buttermilk to make the cake? Please reply back at itran1@hotmail.com. Thank you!
Hi Isabella! Whole milk should work just fine, but buttermilk makes it extra moist. I do have a recipe for DIY buttermilk (using whole milk + vinegar) in the notes of the recipe so if you can’t find buttermilk that would be my next recommendation.