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!
How to make chocolate mousse cake
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 until wooden toothpick inserted in the center comes out clean. Cool to room temperature.
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.
Tips
- 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.
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 fridge for up to 5 days.
More chocolate cake recipes!
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Chocolate Mousse Cake
Equipment
- 9x13-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 9x13-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. Updated with additional photos and tips 2/5/21.
Cake portion adapted from Food Network.
Reader Interactions
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Comments & Reviews
Anje says
This cake is delicious. I made it yesterday and could not stop tasting the mousse while decorating the cake. My family did not like the salt. Was I suppose to grind the salt before placing it in the cake? I poured the kosher salt just like that into the mix. ?
Kate says
Thank you! I love baking with kosher salt, but the salt shouldn’t be noticeable. If you prefer, just use half the amount of table salt (1/2 teaspoon), and that should take care of it. Thanks for coming back to comment! =)
Nancy says
Delicious! Huge hit with my co-workers! Making it again this weekend for family.
Kate says
Thank you! I’m glad that it was a hit, and I hope your family likes it. =) Thank you for coming back to comment.
Emily Stodghill says
Wow! This cake is delicious and very moist. It was my first time ever making a chocolate cake and I was worried somehow it would come out dry. It did not!
I live at a High Altitude and made these adjustments (below) and it turned out beautifully for anyone else wanting to make them. (*Note, I live in Colorado, which is a mile high, if you live higher or lower, you may need to adjust further.) It does end up looking like a very watery mixture for cake, but the crumb turned out for me.
I used two 9″ dark cake pans so my temperature stayed the same and for the high altitude I took them out at 25 minutes because that’s when they seemed done with the toothpick test. (The time may vary for where you’re at so just check it sooner.)
1 3/4 c + 2 Tbsp all-purpose flour
1 3/4 c – 2 Tbsp granulated sugar
3/4 c. unsweetened cocoa powder
1 1/2 tsp. baking soda
3/4 tsp. baking powder
1 tsp. kosher salt
1 c. + 2 Tbsp buttermilk low-fat ok
1/2 c. vegetable oil
2 large eggs + 1 egg white
2 tsp. vanilla extract
1 c. 2 Tbsp hot water not boiling
Kate says
Thank you so much!! I can’t test high altitude adjustments, so it’s extremely helpful when someone can share what’s worked. And congrats on making your first chocolate cake! =)
Nette says
Can I make this the day before? I am a cook not a baker:-)
Kate says
You can! I recommend storing it, covered, in the fridge if you make it the day before. Then, you can either serve it straight from the fridge, or set it out about 10-15 minutes before serving to let the temp come up a bit on it. Good luck! =)
Sharon Scofield says
I live at altitude 5,000. do I need to adjust any of the ingredients? Would it be ok to use 1 regular egg & 1 egg white and substitute applesauce for oil?
Kate says
I’m not sure! I’m hesitant to make suggestions when I haven’t had a chance to try them out. Have you ever tried plain, nonfat Greek yogurt as an oil substitute? If you haven’t, I highly recommend it. I use it all the time, and I find that it gives the cake a more true (less spongy) texture than applesauce.
sonja says
love this recipe easy to make
Kate says
Thank you so much! =)
Orlanda says
Easy to make an was delicious
Kate says
Thank you! I’m glad you liked it! =)
Elise says
Just wanted to share- I found your recipe on Pinterest over a year ago, and have since made this cake almost a dozen times. My family LOVES it. They request it for all special occasions. Today is my son’s 11th birthday, and I will once again be making your cake! Thank you for a delicious recipe!
Kate says
Love it! Your comment made my day. =) I’m so glad that you have enjoyed it, and happy birthday to your son!!
Lucretia DeVore says
Thanks for sharing the Choc. Mousse cake. It sounds delicious. This next weekend is our school reunion. I will make it then for my company.
Kate says
Thank you! I hope you enjoy it! =)
Lori says
Made this for a coworker, huge success! It’s so moist and the mousse frosting is amazing. Everyone loved it including me!
Kate says
Yay! I’m so glad that everyone liked it! Thank you for coming back to leave a comment! =)
Irene Loh says
Hi Kate,
Would love to try your chocolate mousse cake, quick question, can I use this mousse to make a layer cake with 2 layers of cake and mousse?
Kate says
Hi! I’ve never tried making this as a layer cake, and so I’m not sure how the mousse would hold up between the layers. However, I think it would be ok. I’m just not 100% sure.
Nicole M says
Absolutely awesome..the cake is super moist and I thought the chocolate mousse would be too sweet bc of the marshmallows but not at all..whole family loved it! Thank you so much..this is going to be a staple in my recipe box!
Kate says
Thank you! I love to hear that people are enjoying my recipes! Thank you for taking the time to come back and comment!
Heather says
This was the best ‘scratch’ cake I have ever had! I used two different cocoas; Dutch processed (1\2 c) and black cocoa (1\4c). I also used a 10″ square pan for a little thicker cake. This recipe will definitely be my go-to chocolate cake. Thanks for sharing!
Kate says
Yay!! I’m sure your cake was so pretty! I love the way that black cocoa looks in a cake. Thank you for taking the time to come back and comment.
Vdg says
Substitute for marshmallows could be 7 minute frosting. Probably cut the recipe for the frosting in half.
Kate says
Interesting idea! I love 7 minute frosting but haven’t tried it with this mousse. I’d love to hear how it works if you try it!
Apoorva says
Hi! the recipe sounds absolutely delicious but is it possible that you could tel the quantity of marshmallow in grams since I’ll have to use the bigger ones that are available where I live…
thanks :)
Kate says
Sure! You’ll need 65 grams worth of marshmallows. Hope that helps!
Jessica says
Hello, I made this cake and I absolutely loved it. I was just wondering if I could use this recipe to make cupcakes? And If so, how long should I bake it them and what temperature should I them at? Thank you so much
Jessica says
bake them at *
Kate says
Thank you! I’m glad you liked it! I haven’t tried, but I would guess that you can. Usually (and I haven’t tested it with this specific recipe to say for sure), you can keep the oven temp the same. The baking time for cupcakes *should* be about 15-25 minutes. Hope that helps! =)
Diane says
Can you make this cake ahead of time and freeze it?
Kate says
I think that it would be ok to freeze the cake, but I would freeze it unfrosted. I think the frosting might separate if frozen, so I would wait until you’re ready to serve the cake to frost it.
Heather says
I do not like cake usually because the icing is too sweet or the cake comes out too dry. This is my new FAVORITE cake recipe! The mousse is perfect – I love the texture with the marshmallows. You could also use Cool Whip in place of the fresh whipped cream to save time :) Love it!
Kate says
Yay!! I don’t like most sweet icings either, but I’m so glad that you liked this cake! =D
Lou Ann Dawkins says
You have so much patience! Why is it that so many people want to change all of the recipes? Their questions are so annoying! Your recipe appears to be fine as it is printed…
Kate says
Thank you!
Kim McCune says
I made this and thought it was fabulous. The only negative comments I got were from a few people who thought the mousse was too bitter. Can you use milk chocolate instead of semi sweet? Thanks!
Kate says
Absolutely! Semi sweet is just my preference, but I’m sure that milk chocolate would work, too.