Elegant, moist and delicious Chocolate Mousse Cake recipe filled with an easy homemade chocolate mousse, and warm chocolate frosting poured on top.
Want more cake recipes? Try my German Chocolate Cake, Berry Cake, or Coconut Cake with Pineapple Filling!
Why I love this easy mousse cake:
- Prep Ahead – The chocolate mousse recipe couldn't be easier to make, and you can prep everything in advance!
- Elegant – Fancy enough to impress any guests, especially a chocolate lover!
- Delicious – The chocolate cake is moist and divine. The chocolate mousse filling is creamy and pairs perfectly with the cake. This will become your new favorite cake!
How to make Chocolate Mousse:
Make the Mousse: Start by mixing the cocoa powder and hot water together until smooth. Melt chocolate chips in the microwave, or using a double boiler. Add the cocoa powder mixture to the melted chocolate and stir until smooth. Allow to cool to room temperature.
Whip the cream and sugar together in a large mixing bowl until very stiff peaks. Add the cooled melted chocolate and gently fold the mixture together to combine. Refrigerate until ready to use.
How to make Chocolate Mousse Cake:
Bake Chocolate Cake: Stir together sugar, flour, cocoa powder, baking powder, baking soda, and salt in a large bowl. Add eggs, milk, oil, and vanilla. Beat on medium speed for 2 minutes. Stir in boiling water then pour into prepared pans. Bake at 350 degrees for 30-35 minutes, or until a toothpick inserted comes out clean. (If you don't want to make the cake from scratch, you can use a box cake mix).
Halve the Cake Rounds: Once the cakes have cooled use a sharp serrated knife to torte them in half, lengthwise, so you have four thin layers of chocolate cake.
Stack Cake with Mousse Filling: Place the first cake layer on your serving tray. Smooth a thin layer of chocolate mousse over it, and top with the next layer of cake. Repeat to assemble a cake with chocolate mousse between each layer. Smooth any extra chocolate mousse you have over the outsides of the entire cake to make a”crumb” coat to seal the cake.
Refrigerate the cake for at least 30 minutes (or up to 1-2 days, covered) while you make the chocolate frosting.
Make Frosting: Combine milk, cocoa, and butter in a medium saucepan. Bring to a boil then remove from heat. Add powdered sugar and mix with electric beaters to get rid of any lumps. Cool for at least 15-20 minutes, stirring occasionally. Be sure to allow the frosting to cool long enough. You want it soft enough to still be “pourable” but you don't want it to be so warm that it melts the mousse into a puddle.
Pro Tip: Lay pieces of parchment paper around, and gently under the edges of the cake to catch the frosting as it drips down. I usually just pour the frosting slowly and catch it as it comes down the sides of the cake, smoothing it along the sides of the cake.
Make Ahead Instructions:
- Chocolate Mousse: Place in an airtight container in the fridge for up to 5 days. Fold it again gently with a spatula before using. But the texture is best the day of.
- Cake Rounds: These can be made in advance and frozen. Once baked, cool them completely and then wrap them in a double layer of plastic wrap. Place in a freezer safe bag and freeze for up to 3 months.
More Desserts to Try:
- Chocolate Peanut Butter Cake
- Meringue Roulade
- Chocolate Milkshake
- S'mores Bars
- Panna Cotta
- Tres Leches Cake
- World's Best Peanut Butter Bars
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Recipe
Chocolate Mousse Cake
Equipment
Ingredients
Chocolate Cake:
- 2 cups granulated sugar
- 1 3/4 cups + 2 Tbsp all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/2 teaspoons baking powder
- 1 1/2 teaspoons baking soda
- 1 teaspoon salt
- 2 large eggs
- 1 cup buttermilk
- 1/2 cup oil (vegetable or canola oil)
- 2 teaspoons vanilla extract
- 1 cup boiling water , or hot coffee
Chocolate Mousse:
- 1/2 cup hot water
- 4 Tablespoons unsweetened cocoa powder
- 1 1/2 cups semi-sweet chocolate chips
- 2 cups heavy whipping cream
- 2 Tablespoons granulated sugar
Chocolate Frosting:
- 6 Tablespoons milk
- 3 Tablespoons unsweetened cocoa powder
- 1/2 cup butter (one stick)
- 3 3/4 cups powdered sugar
Instructions
Chocolate Cake:
- Heat oven to 350°F. Grease and flour two 8 or 9 inch round baking pans. (I like to line the bottom of mine with wax or parchment paper).
- Stir together sugar, flour, cocoa powder, baking powder, baking soda and salt in large bowl.
- Add eggs, buttermilk, oil and vanilla; beat on medium speed of mixer 2 minutes.
- Stir in boiling water (the batter will be thin). Pour batter into prepared pans.
- Bake for about 30 to 35 minutes or until a toothpick inserted in the center comes out clean.
- Allow cake to cool in the pan for 5 minutes and then remove to wire cooling racks. Cool completely. (You could freeze the cake rounds at this point, if desired.)
Chocolate Mousse:
- Stir the cocoa powder and hot water together. In a double-boiler (or in the microwave) melt the chocolate chips, just until smooth. Add the cocoa mixture to the melted chocolate chips and stir well to combine. Allow to cool to room temperature.
- In a separate large bowl, beat the cream and sugar until very stiff peaks form. Add the chocolate mixture and fold in with a spatula until well combined. Refrigerate until ready to use, up to 5 days.
Chocolate frosting:
- In a medium saucepan, add milk, cocoa, and butter. Bring to a boil. Remove from heat.
- Add powdered sugar and mix with electric beaters to get rid of any lumps. Allow to cool for 15-20 minutes, stirring occasionally.
Assembly:
- Once cakes have cooled, use a sharp serrated knife to torte each cake (cut each cake evenly in half, horizontally, so that you end up with four, thin, 9” cake pieces).
- Place your first cake layer on your cake serving plate. Spread a big spoonful of mousse on top of that cake layer. Repeat with the remaining cake layers, adding a layer of mousse filling between each layer of cake.
- Use remaining mousse filling to spread it evenly around the entire outside and top of the cake. Refrigerate for 30 minutes.
- (I usually make the warm chocolate frosting while the cake is in the fridge.)
- Remove cake from fridge and very slowly pour the cooled chocolate frosting over the top. Use a spatula or knife to gently spread the frosting evenly over the outside of the cake as you pour.
- Refrigerate until ready to serve.
Notes
- Mousse: Place in an airtight container in the fridge for up to 5 days. Fold it again gently with a spatula before using. But the texture is best the day of.
- Cake Rounds: These can be made in advance and frozen. Once baked, cool them completely and then wrap them in a double layer of plastic wrap. Place in a freezer safe bag and freeze for up to 3 months.
Nutrition
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*I first shared this recipe in May 2014. Updated May 2018 and February 2022.
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This cake recipe is amazing!! I made it for my dad for Father’s Day and I couldn’t believe how moist, chocolatey and delicious it was. I’m always nervious making things from scratch because I’ve had some prior mishaps, but I’ll definitely keep this as my go-to chocolate cake recipe 🙂
I’m so happy to hear eat!!! Thanks Natalie!
Hi. My husband absolutely loves chocolate cake. His birthday was today. I ran across this recipe and knew I had to try it for him. It was absolutely a hit. There was only one problem. The frosting ran everywhere! It was delicious, but I had an absolute mess and couldn’t get much to stay on. Any tips on maybe what I did wrong or what I can try in the future? Thank you so much! Everything else was perfect and my husband loved it even if it was a mess 🙂
Hi Trina, I’m happy your husband liked the cake–sorry you had some trouble with the frosting. Next time you could add some powdered sugar to thicken it up and/or let it cool a little longer so it is easier to frost. Make sure you have a good spatula (I use an offset spatula) to smooth the frosting around the cake as you slowly pour it. You don’t need to pour it all at once, just little by little so you have time to smooth it around the cake as you go 🙂 Hope those tips will help you next time!
I had the same issue and was so disappointed given the time I spent making this. When I poured the frosting over it, the warmth melted the mousse and it ran all down the sides and was a mess. It may taste ok but it looks less than good. I would suggested eliminating the mousse from the top and sides.
This looks so GOOOD! …and you are right, not so hard to follow. Thanks for sharing, I am definitely pinning this!
I just found your site from My Recipe Magic. I am so excited! I have always baked from scratch. I don’t understand why people use cake mixes. The one that really befuddles me is pie crust mixes. Who needs a mix for flour, shortening, salt and whatever you choose for your liquid? This cake sounds amazing. I can’t wait to try it. I am also signing up for your email notifications. I don’t want to miss one of your recipes. I received my first cookbook when I was in the first grade. I am now 57 years old. I make our bread every week and love to be in the kitchen. I’m so glad I found you.
You are so sweet, thank you so much for your nice comments! I completely agree–who needs a cake mix or a pie crust mix when they probably already have everything they need to make it from home! (And it tastes so much better too!). I’m so happy you’re following along. I’d love to hear which recipes you try 🙂
My 9 1/2 year old is doing a cake decorating class to earn an honor badge for Pathfinders (a youth organization similar to Scouts). She’s also working on her baking honor badge, since the two seem to go hand-in-hand, and needed to make a cake from scratch. I helped her find this recipe, and she did the work. Since she was decorating it, she only used the cake and mousse filling portions of your recipe. I just had to help her put the pan in the oven because it was heavy (we made a double recipe in a 12x18x2 rectangle pan).
OH MY WORD, this is the BEST chocolate cake I’ve ever tasted. Simply amazing. It is definitely going in my recipe file.
That is so fun to hear about your daughter–How impressive! So happy you enjoyed the cake!! Thanks for commenting 🙂
This was by FAR the best chocolate cake I’ve ever made. Since making it for the first time last month, I’ve had three other people request it. You are a genius! 🙂
What a compliment! Thanks Parker! I’m glad you think it’s a winner too 🙂
This looks wonderful! I am excited to make it for my boyfriend’s birthday! We’re going to be a party of 20. Being a baking amateur, do you mind providing measurements for a doubled recipe? I know it’s important to be mathematically precise! Thank you 🙂
Hi Tess, here are the measurements to make double: Have fun at the party–I’d love to hear how you like the cake!
For the Cake:
4 cups sugar
3 1/2 cups flour
1 1/2 cups cocoa powder
3 tso baking powder
3 tsp baking soda
2 tsp salt
4 eggs
2 cups milk
1 cup vegetable oil
1 Tbsp vanilla extract
2 cups boiling water
For the mousse:
1 cup hot water
1/2 cup cocoa powder
3 cups semi-sweet chocolate chips
4 cups heavy cream
1/4 cup sugar
For the Frosting:
3/4 cup milk
6 Tbsp cocoa powder
1 cup butter (2 sticks)
7 1/2 cups powdered sugar
Awesome! Thank you so much! Can’t wait to tell you how it comes out 🙂
I found this cake on Pinterest, and I knew I had to give it a try. I have been craving a good chocolate cake for some time now, and this looked like it would fit the bill. I have never made a cake from scratch before, and I have never whipped cream before. I was in charge of dessert for Easter, so I gave it a try. It was very easy to make, but there are a lot of steps. The cake was moist and delicious. When I made the mousse, I thought it tasted a little bitter, so I wasn’t sure how that was going to taste. I got he cake all put together and made the chocolate frosting. I poured it over the top, and boy did it make a mess! Perhaps your could give some hints as to how to avoid making such a mess. Anyway, the cake was delicious. I loved the chocolate frosting, it tasted like fudge. The mousse tasted great, it could hav ebeen a little sweeter for me though. This cake is very rich, and very good!
I’m just wondering what’s best/ how to store this cake if its using double cream? Best to leave in the fridge til served? How many days will it last? Thanks
Hi Sophie, Yes you can leave it in the fridge covered (I like to just place a huge bowl over the top). It will keep for at least 2-3 days. Let me know how you like it! 🙂
Bad News: My cake was NOT pretty
Good News: The flavor was AMAZING