Easy chocolate mousse cake recipe makes a moist dark chocolate cake that’s topped with a simple, easy chocolate mousse. Easy homemade cake recipe that always gets rave reviews!
I like chocolate mousse anything – Chocolate Mousse, French Silk Brownies, and chocolate mousse brownies are just a few of the chocolate mousse treats that I love! So it isn’t surprising that this chocolate mousse cake is one of my favorite cake recipes!
This cake is moist and intensely chocolaty. It’s topped with a super rich and creamy chocolate mousse for the ultimate chocolate dessert.
And all of that chocolate in one little piece of cake means a super delicious dessert that’s perfect for birthdays, holidays, or any time you want something a little extra!
“The absolute best chocolate cake I’ve ever made. I used 2% because I didn’t have buttermilk. The mousse was incredible. I’ll definitely be make this over and over.” – Jessica
Ingredient notes and substitutions
- Cocoa powder: I use regular unsweetened cocoa powder in this recipe. I’ve also used Hershey’s special dark cocoa powder. However, I haven’t tried Dutch-processed cocoa powder with this cake.
- Salt: If you don’t have kosher salt, use 1/2 teaspoon table salt instead.
- Buttermilk: Regular or low-fat will work. If you don’t have buttermilk, you can make a quick substitute with this recipe.
- Oil: Feel free to use another type of neutral oil like canola oil or olive oil.
- Water: I use hot tap water about (150F).
- Semisweet baking chocolate: If you’d like a sweeter mousse, you can use milk baking chocolate.
- Milk: Any milk from skim to whole milk will work.
How to make chocolate mousse cake
Here you’ll find step-by-step photos showing how to make this recipe. The full recipe, including ingredients, is given below.
Step 1: In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
Step 2: In a large bowl, whisk together buttermilk and vegetable oil. Whisk in eggs one at a time.
Step 3: Stir in dry ingredients until just combined.
Step 4: Add hot water and vanilla. Whisk until just combined.
Step 5: Pour batter into prepared baking dish.
Step 6: Bake until wooden toothpick inserted in the center comes out clean. Cool to room temperature.
Step 7: To make the chocolate mousse, add mini marshmallows, chocolate, and milk to a large, heavy saucepan.
Step 8: Cook over low heat, stirring constantly, until melted and well-combined. Remove from heat, and cool completely.
Step 9: In a large bowl, beat whipping cream and vanilla together to soft peak stage.
Step 10: Fold whipped cream into cooled chocolate mixture.
Step 11: Spread over cooled cake. Chill for at least 30 minutes, or until ready to serve.
Recipe Tips!
- Metric: You can the weights for the ingredients by clicking on “metric” immediately above the ingredients.
- Grated chocolate: I grate a little chocolate over the top of the cake for looks and a bit of texture.
Recipe FAQs
This recipe has had hundreds of comments and questions. Here are some answers to some of the most commonly asked questions.
You can! The cake freezes well. Once the baked cake has cooled to room temperature, wrap it tightly in plastic wrap and then wrap it in aluminum foil. The cake will keep for up to 1 month in the freezer.
No, you can’t taste the marshmallows in the mousse. They help to make it light and fluffy, but it tastes like chocolate, not marshmallows.
The cake keeps well in the fridge. You can make it up to 1 day before serving and store it in the refrigerator.
Tips for making whipped cream
If you haven’t made whipped cream (or would just like some tips), I have lots of tips and more pictures here.
Storage
The cake can be stored, covered, in the refrigerator. It will keep for up to 5 days when properly stored in the fridge.
More chocolate cake recipes!
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Chocolate Mousse Cake
Equipment
- 9×13-inch metal baking pan
Ingredients
Chocolate Cake
- 1 ¾ cups all-purpose flour
- 1 ¾ cups granulated sugar
- 3/4 cups unsweetened cocoa powder
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 1 teaspoon kosher salt
- 1 cup buttermilk
- 1/2 cup vegetable oil
- 2 large eggs
- 2 teaspoons vanilla extract
- 1 cup hot water not boiling
Chocolate Mousse
- 1 ½ cups mini marshmallows
- 8 ounces semisweet baking chocolate chopped
- 1/2 cup milk
- 2 cups cold heavy whipping cream
- 1/2 teaspoon vanilla extract
Instructions
Chocolate Cake
- Preheat oven to 350 F. Grease a 9×13-inch baking pan. Set aside.
- In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
- In a large bowl, whisk together buttermilk and vegetable oil.
- Whisk in eggs one at a time.
- Stir in dry ingredients until just combined.
- Add hot water and vanilla.
- Whisk until just combined.
- Pour batter into prepared baking dish.
- Bake 30-40 minutes, or until wooden toothpick inserted in the center comes out clean.
- Cool to room temperature.
Chocolate Mousse
- To make the chocolate mousse, add mini marshmallows, chocolate, and milk to a large, heavy saucepan.
- Cook over low heat, stirring constantly, until melted and well-combined.
- Remove from heat, and cool completely.
- In a large bowl, beat whipping cream and vanilla together to soft peak stage.
- Fold whipped cream into cooled chocolate mixture.
- Spread over cooled cake.
- Chill for at least 30 minutes, or until ready to serve.
- Refrigerate any leftovers.
Video
Notes
- Cocoa powder: I use regular unsweetened cocoa powder in this recipe. I’ve also used Hershey’s special dark cocoa powder. However, I haven’t tried Dutch-processed cocoa powder with this cake.
- Salt: If you don’t have kosher salt, use 1/2 teaspoon table salt instead.
- Buttermilk: Regular or low-fat will work. If you don’t have buttermilk, you can make a quick substitute with this recipe.
- Water: I use hot tap water about (150F).
- Semisweet baking chocolate: If you’d like a sweeter mousse, you can use milk baking chocolate.
- Milk: Any milk from skim to whole milk will work.
- Nutrition facts are estimates.
Nutrition
Did You Make This Recipe?
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Originally published 10/14/16. Post is updated regularly with new photos, tips, and information.
Cake portion adapted from Food Network.
Reader Interactions
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Comments & Reviews
Debbie says
Please clear something up for me. You show pictures using a porcelain pan and a metal pan which is indicated in the recipe. I saw someone say that a glass pan wasn’t tall enough; what is the proper pan to use? I am anxious to make this cake and want to get it right.
Kate says
Hi! I’ve used 9×13-inch metal and ceramic pans to make this cake, and I haven’t had issues with either. I’m not sure why someone would say that unless they mistakenly used a different sized glass pan. The only difference I could see would be that you might need to reduce the baking temperature 25F if using a glass pan.
Angie says
We loved, loved, loved this cake.
Marilyn says
I used a 9×13 Pyrex lasagna pan because the sides are higher, and it worked perfectly!
Kate says
Thank you!
RickyLynn says
This cake is delicious! I’ve made it 4 times in the last month for different occasions. Everyone that has eaten it loves it!
Kate says
Thank you!!
Christy says
I have made this cake twice in the last month. It is delicious! It is rich and yet light. Even after a few days in the fridge, the leftovers have stayed moist and delicious. I have used coffee instead of water both times and it has worked great. I like to shave a milk chocolate bar over the top and serve with some coffee ice cream.
Kate says
Thank you so much!
Megan says
Hi- this cake is amazing. Do you have a homemade yellow or white cake recipe too?
Kate says
Hi! Thank you! Here is my yellow cake recipe. I don’t have a white cake recipe up yet.
Ly says
Just to let you know – Hershey’s Special Dark is Dutch Processed
Kate says
Thank you for that!
Misty says
Hello, can this be made in two round pans for a birthday cake? Any advice for doing so?
Thank you for the recipe!
Kate says
Hi! I think the cake would work well in a round pan. I would chill the frosted lower layer to let it set up before topping with the top layer. Otherwise, the top layer made smash the mousse or slide off the lower layer. Hope that helps!
Doris says
Hi, I want to do this as a small round cake in 2 layers, is there any way to thicken the mousse so it can be in-between the layers as well as the frosting? Thanks :)
Kate says
Hi! I haven’t tried to make the mousse any thicker. I’ve heard from a few people who have make this cake into a layer cake.
Janet says
Amazing chocolate cake! And the frosting is to die for ?
Kate says
Thank you so much!!
Korie says
I made this for my mom’s birthday this weekend and everyone loved it. Adding this to our make again list for sure!
Kate says
Yay!! I’m so glad that it was a hit!
Karen Cornell says
This was one of the best chocolate cakes I’ve eaten in a long time. It was so moist and flavorful. Easy to make
The mousse as well was easy to make and so delicious. This is definitely a keeper recipe.
Kate says
Thank you so much! I’m glad you liked it!
Nicki says
Could this recipe be used for cupcakes?
Kate says
I would guess so, but I haven’t tried it!
Linsey says
Hi Kate!
I was thinking of making this is 2 round 9 inch pans. Do you know if the chocolate mousse would hold well as a layer between the cakes?
Thanks!
Kate says
Hi! The chocolate mousse is pretty soft when you first make it. You may have better luck frosting the first layer and then chilling until firm and then placing the second layer on top and then finishing the cake that way. Hope that helps!
Swathi says
Hey, thanks a ton for the recipe.. Is it possible to substitute the marshmallow with something else? I’m finding it really hard to find a pack of marshmallows at the moment?? and it’s my boyfriend’s bday cake, I want it to be perfect.. Any recommendations please? Thanks much!?
Kate says
I wish I had an easy substitute for you! Unfortunately, if you can’t find marshmallows, you’d need to find another mousse recipe because the marshmallows provide a lot of the stability for the mousse.
Donna says
Can you use hot coffee instead of water?
Kate says
Hi! I haven’t tried using coffee in place of the water, but I’ve heard from people who have made that swap, and they’ve said that it worked out well for them.
Laura says
This was incredible!!
Kate says
Thank you so much!
Suzie says
Hello!
This cake sounds divine!
Just wondering if I could make cupcakes with it and if so, what the baking time would be?
Kate says
Hi! I haven’t tried making cupcakes with this recipe, but I don’t see why it couldn’t work. The baking time for cupcakes is usually about 18-25 minutes.
Malinda Long says
I made cupcakes with your recipe. It made 24-30. So delicious. My families favorite. Thank you.
Kate says
Thank you! I’m glad your family liked them!
Brooke says
Going to make this cake for my sons 3rd birthday! Would you happen to know the baking time for two 9” round pans ?
Kate says
For a 9″ round cake, it’s usually about 20-30 minutes.
Taryn says
My D loves the tuxedo cake from Costco. I hate baking! But she turned 11 in March 25th (during the dreaded QUARANTINE!) Hubby is germaphobe & hypochondriac so he was freaking out Bc I wanted to order or p/u the tuxedo cake. So I didn’t??
So, during this time…ordered groceries ( several times now) however, I guess EVERYONE LOVES baking except me…Bc I guess all the regular flours are out?!?! Shopper brought me…Arrowhead Mills all purpose flour ( but Gluten Free!!!)
I think this recipe is easy & I really truly think it would have turned out FAB…but that D GF flour!!!!! Made it extremely gritty!!! I was so sad! My D ate it anyway & we all did….Bc the mousse was delish! And the cake…..I truly think it would have been wonderfully chocolate delicious if it weren’t for that flour.
I hope to try it again 1 day…especially the mousse!
Thank you for the recipe especially since I’m an amateur.
Kate says
I hope your daughter had a very happy birthday!! My older daughter has a birthday coming up soon, and it’s hard for the kids who have birthdays during the quarantine. I’m glad that the mousse was good at least! If you ever have any questions as you go, please feel free to ask!
Ashley says
Hi!! Can the mousse be made and put in the fridge until ready to spread on the cake? I used a 9×13 glass dish but the cake baked right up to the top!! There’s no room for the mouse lol so I figured I would just chill the mousse and then slather it on when we are ready to eat it! Then I won’t care if it goes over the pan ha as I need to travel with it tomorrow!
Thanks!!
Ashley
Kate says
Hi! I think that should work! The mousse keeps well in the fridge, so it should be fine to chill it until you’re ready to serve the cake.
Kristie krebs says
Making this for a birthday cake for a chocolate loving ten year old! Can you make it a day early or is it better theday of?
Kate says
Hi! I haven’t found much difference between the cake on the first and second days. The only difference I’ve noticed is that the mousse sets up a bit in the fridge, and so you may find that you want to let it sit out just a bit if it’s firmer than you want it to be.
Taryn says
We ate it several days after my D b day (& if you read my above comment…my cake was gritty Bc of GF flour HOWEVER…it was still decent) you could make it day before & still eat it several days later…. it’s still very good Bc the mousse is yum. Happy B Day to yours & mine during h th his dreaded time!?❤️
Janine says
Hi I was thinking about making this for my birthday tomorrow the problem I have Is I only have the big marshmallows . Do you have a thought on how many you think I might need ? I know in this very stressful time you might not have moment but if you do I would appreciate it . God bless stay safe.
Kate says
Hi! Happy (early) birthday!! I do! Five regular (larger) marshmallows should equal 1/2 cup. So, you’ll need 15 of the larger marshmallows. Thank you for your kind words, and I hope you stay safe, too!
Mayra Sandoval says
This is so delicious ? u did a 3 layer for my birthday, because I wanted it to be perfect lol and it was everything I wanted. How can I post a picture?
Kate says
Happy birthday to you! I don’t have any way to accept uploads on here, but if you post it on social media, please let me know. I’d love to see it!
Kim says
This is one of my favorite cakes to make. Is it possible to sub the flour and sugar with almond flour and Erythritol?
Kate says
Thank you! I’m not sure! It’s hard to say whether the almond flour would work well or whether other changes would be necessary without having tested it. I wish I had a better answer for you!