Chocolate Mousse Cake

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Right after Mother’s Day, we celebrated my husband’s birthday, and I knew there was only one dessert that would make him truly happy—a chocolate cake. Chocolate is his absolute favorite, so I wanted to make something extra special. Since I had leftover chocolate mousse from my Mother’s Day crepes, I decided to turn it into a decadent chocolate mousse cake, layers of chocolate cake with creamy mousse and smooth buttercream frosting.

The result? A tasty, crowd-pleasing dessert that was a huge hit with my husband and the whole family! It’s a chocolate lover’s dream! The best part is that you can use any moist chocolate cake layers as the base—whether homemade or store-bought. I kept it simple by using a boxed cake mix for the chocolate cake base, which made the process easy while still delivering an impressive, bakery-style dessert. This cake is proof that you don’t need complicated techniques to create something beautiful, delicious, and celebration-worthy!

Chocolate Mousse Cake | realmomkitchen.com
  • 2 PREPARED 8″ OR 9″ ROUND CHOCOLATE CAKES (I JUST USED A BETTY CROCKER CHOCOLATE FUDGE CAKE)
  • UNFLAVORED GELATIN
  • COLD WATER
  • BOILING WATER
  • SUGAR
  • HERSHEY’S COCOA
  • COLD HEAVY CREAM
  • VANILLA EXTRACT
  • BUTTER
  • SALT
  • POWDERED SUGAR
  • MILK

Make the Chocolate Cake: I just baked a Betty Crocker Triple Fudge Cake according to the package instructions. Then pour the cake batter into two 9-inch round cake pans and cook according to the package for those size pans. For easy removal, I line the bottom of the pans with parchment paper. Allow to cool on a wire rack.

Make the Chocolate Mousse: In a small cup, sprinkle gelatin over cold water and let it sit for 1 minute to soften. Add boiling water and stir until the gelatin is completely dissolved. Let it cool slightly. In a medium bowl, mix sugar and cocoa powder, then add whipping cream and vanilla extract. Beat on medium speed until the mixture forms stiff peaks, scraping the bottom of the bowl occasionally. Pour in the gelatin mixture and beat until fully blended. Store the mousse in the refrigerator while preparing the frosting.

Make the Chocolate Buttercream Frosting: In a mixing bowl, beat butter, cocoa powder, and vanilla extract on medium speed until creamy. In a separate bowl, whisk together powdered sugar and cocoa powder. Gradually add the powdered sugar mixture to the butter mixture, alternating with 3 tablespoons of milk, 1 tablespoon at a time, beating at low speed until smooth. If needed, beat in up to 4 additional tablespoons of milk to reach your desired frosting consistency.

Assemble the Cake: Place one cake layer on a serving plate and spread the chocolate mousse evenly over the top using an offset spatula. I like to top it with 2/3 of the mousse mixture. Carefully place the second cake layer on top. Then I use the remaining mousse mixture to fill in the sides so it is even with the sides of the cake.

Frost the entire cake with chocolate buttercream frosting, being gentle around the mousse layer to prevent mixing. Refrigerate the cake until ready to serve. For best texture, let it sit at room temperature for a few minutes before serving to soften the frosting.

Can I make the mousse ahead of time?
Yes! You can prepare the mousse up to 24 hours in advance and store it in the refrigerator until you’re ready to assemble the cake.

How do I prevent the mousse from mixing into the frosting?
When frosting the cake, gently spread the buttercream over the mousse layer without pressing too hard. Using a piping bag to apply frosting around the edges first can help create a clean barrier.

How long should I refrigerate the cake before serving?
Keep the cake in the refrigerator until ready to serve, but let it sit at room temperature for 15-20 minutes before slicing to soften the frosting.

Can I freeze this cake?
Yes! You can freeze the assembled cake for up to 3 months. Wrap it tightly in plastic wrap and store it in an airtight container. Thaw in the fridge overnight before serving.

What toppings go well with this cake?
Try garnishing with chocolate shavings, fresh berries, whipped cream, or a dusting of cocoa powder for an elegant touch.

Chocolate Mousse Cake | realmomkitchen.com

Chocolate Mousse Cake

Real Mom Kitchen

This chocolate mousse cake is a rich and indulgent dessert featuring layers of fluffy chocolate cake, creamy mousse, and smooth buttercream frosting. It’s easy to make using a boxed cake mix, yet looks incredibly impressive for any special occasion. Whether you're celebrating a birthday or simply craving a decadent treat, this cake is sure to be a hit with chocolate lovers!
5 from 1 vote
Print Recipe Pin Recipe
Prep Time 40 minutes
Cook Time 30 minutes
Cooling/chill time 1 hour 30 minutes
Total Time 2 hours 40 minutes
Course Cake, Dessert
Cuisine American
Servings 16 servings
Calories 658 kcal

Ingredients
  

Cake:

  • 2 prepared 8″ or 9″ round chocolate cakes I just used a Betty Crocker Chocolate Fudge cake

Chocolate Mousse:

  • 2 tsp unflavored gelatin
  • 2 Tbsp cold water
  • 4 Tbsp boiling water
  • 1 cup sugar
  • ½ cup HERSHEY’S Cocoa
  • 2 cup cold whipping cream
  • 2 tsp vanilla extract

Frosting:

  • ¾ cup butter softened
  • 1 ½ tsp vanilla extract
  • teaspoon salt
  • 6 cups powdered sugar
  • 1 cup HERSHEY’S Cocoa
  • 7 Tbsp milk

Instructions
 

  • To make the mousse: Sprinkle gelatin over cold water in small cup; let stand 1 minute to soften. Add boiling water; stir until gelatin is completely dissolved. Cool slightly.
  • Stir together sugar and cocoa in medium bowl; add whipping cream and vanilla. Beat on medium speed of mixer, scraping bottom of bowl occasionally, until mixture is stiff. Pour in gelatin mixture; beat until well blended. Store in the refrigerator while you make the frosting.
  • To make the frosting: Beat first 3 ingredients at medium speed with an electric mixer until creamy.
  • Whisk together powdered sugar and cocoa. Gradually add powdered sugar mixture alternately with 3 Tbsp. milk, 1 Tbsp. at a time, beating at low speed until blended and smooth after each addition. Beat in up to 4 Tbsp. additional milk for desired consistency.
  • To make the cake: Place one of the round cakes on your serving plate and top with chocolate mousse. Top with remaining cake round and frost entire cake with chocolate buttercream frosting. Be careful at the spots where the chocolate mousse is. You need to get the frosting to just cover those spots, if you spread to much in those areas the chocolate mousse can get mixed into the frosting. Keep cake in the refrigerator until ready to serve. You can bring it out a little before serving to allow the frosting to soften.

Nutrition

Serving: 1 serving | Calories: 658kcal | Carbohydrates: 103g | Protein: 6g | Fat: 29g | Saturated Fat: 15g | Polyunsaturated Fat: 4g | Monounsaturated Fat: 9g | Trans Fat: 0.3g | Cholesterol: 57mg | Sodium: 547mg | Potassium: 344mg | Fiber: 4g | Sugar: 79g | Vitamin A: 715IU | Vitamin C: 0.2mg | Calcium: 123mg | Iron: 4mg
Keyword cake, cake mix, chocolate, mousse
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5 from 1 vote

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21 Comments

  1. Hi, I saved and made this recipe back in 2015 and I was looking for it again since I lost it but now there is nothing here for this chocolate mousse cake. Can you please send me the full recipe?? Thank you!

  2. Hi! I followed all of the steps for making the mousse and it looked great until I added the gelatin mixture. Now it’s turned back into more of a liquid. Can you please help?
    Thanks!

  3. Should the cake be refrigerated after it is made because of the mousse filling? i want to make this cake for my daughter’s birthday but I want to cover the cake with fondant and i will not be able to refrigerate the cake once i cover it with fondant.
    Thank you
    bindiya

  4. Pingback: This Chocolate Mousse Cake is sure to please any chocolate lover. | Dreamy Blog
  5. great resources here. I’ll be back for the next your posting. keep writing and happy blogging.

  6. Lori, you should be able to find it near the jello. It is usually found on the top shelf of my grocery store. The brand I use is Knox. It's in packaging that's orange and white with a slice of cheesecake on it. Here's a link to see what the package looks like. https://brands.kraftfoods.com/knox/I hope this helps.

    Laura

  7. Hi! I am hoping to make this cake over the weekend, but I couldn't find unflavored gelatin. Maybe I was looking in the wrong place (Jell-o)? Could you tell me what brand you use and where I can find it at the supermarket?

    Thanks!

  8. Ok, this chocolate mousse cake looks totally perfect! How did you get it to look so even and exact? Beautiful! And your photography skills are excellent. I will definitely have to check back often to see what other treats you create!I just started a baking blog a couple of months ago and would love to share it with you. Please take a moment to check it out and tell me what you think.Sincerely,Heidi

  9. Hi! I just found your blog today. This cake looks SO GOOD! I'm going to have to try it. Hey I had a question about some of the features you have in your blog… Would you mind emailing me at BeantownBaker at gmail dot com? (I'm specifically wondering how you got the Stumble it and bookmark features on each post – I haven't been able to figure that out on blogspot…)

  10. Yes, this picture went through photo shop. I usually have to use photo shop for all my pictures. Lightening is hardly ever perfect for me. That’s probably the thing I have to do the most to help make the picture pretty!

  11. i have to second melanie on the apple tart!! SO easy, SO delicious and now all my friends know about it! i am loving this cake. i am going to make it with my girls tonight while the boys are out camping! YUM!!

  12. This looks amazing…I’m going to try to make this for Father’s Day. I wanted to add…have you seen the apple tart just posted on Pioneer Woman? It’s so easy I’ve been telling everyone about it…

  13. 5 stars
    Laura you are so smart! I never thought to use the chocolate mousse in cake, but this is perfect!!

    Laura