This triple Dark Chocolate Mousse Cake is decadent, yet surprising light. It's made with a super moist chocolate cake base, followed by a light and airy chocolate mousse (made without gelatin), and then topped with a rich chocolate ganache.
As a flavor variation, try my incredible raspberry mousse cake!
The Layers
This chocolate mousse cake is absolutely delicious and a dream for chocolate lovers! The chocolate cake base has been adapted from my chocolate cupcake recipe. Not only does it have a deeply rich chocolate flavor, as we're using Dutch-process cocoa powder, it's extremely moist even cold from the fridge.
The dark chocolate mousse is light and airy and immediately melts-in-your-mouth. It's made without gelatin, but is made with eggs for richness and stability. And don't worry, we'll be cooking the eggs! Instead of tempering them as we would in a custard-style ice cream, it will be cooked directly in the saucepan, slow and low with the mousse mixture to make it even easier. If you'd like an eggless version, I included a recipe in the FAQ section towards the end of the post.
And to tie in all the chocolate flavor, the cake is finished with a silky smooth dark chocolate ganache that is truly irresistible.
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Ingredient Notes
Here are some notes about all the ingredients used in this Dark Chocolate Mousse Cake. Quantities and full instructions are in the recipe card below!
Chocolate Cake
- All-Purpose Flour - I recommend using a kitchen scale to measure your flour with for best results. Adding too much flour can make your cake dry and dense rather than light and moist.
- Unsweetened Cocoa Powder - Make sure you're using Dutch-process cocoa powder. Natural cocoa powder is acidic and would not work with the quantity of leveners we have in this recipe.
- Leveners - We are using a combination of baking powder and baking soda for the perfect rise and texture.
- Fine Espresso Powder - Enhances the chocolate flavor.
- Salt - Rounds out the flavors and balances the sweetness.
- White Sugar - Adds a bit of sweetness and moisture.
- Neutral Oil - The oil makes the cake light and moist.
- Full-Fat Sour Cream - Adds moisture.
- Whole Egg - Adds structure.
- Vanilla Paste or Extract - For flavor.
- Boiling Hot Water - The hot water blooms the espresso and cocoa powder.
Chocolate Mousse
- Heavy Cream - Heavy cream will have 2 applications for this mousse. It will first be cooked with the chocolate mousse mixture, and then whipped to be folded into the cooled mousse mixture.
- Whole Egg + 1 Yolk - Adds richness and helps thicken the chocolate mousse.
- Sugar - Lightly sweetened the mousse.
- Unsweetened Cocoa Powder - Again, we're using Dutch-process cocoa powder for the deep chocolate flavor.
- Fine Espresso Powder - Enhances the chocolate flavor.
- Dark Chocolate Chips - I'm using Ghiradelli 60% chocolate chips. I recommend using between 60% to 70%.
- Salt - Enhances all the flavors.
- Vanilla Extract - For flavor.
*See recipe card for quantities.
Step-By-Step Instructions
Here are step-by-step photos and instructions on how to make this Dark Chocolate Mousse Cake! Please find detailed instructions in the recipe card at the end of this post.
How to make Chocolate Cake
Step 1. Combine Dry Ingredients - In a medium bowl, combine flour, cocoa powder, espresso powder, baking powder, baking soda and salt.
Step 2. Combine Wet Ingredients - In a large bowl, whisk together sugar, oil, sour cream, egg and vanilla.
Step 3. Combine Wet & Dry Ingredients - Sift dry ingredients into the wet ingredients and whisk until nearly combined. The batter will be thick.
Step 4. Add hot boiling water and gently whisk until just combined. Do not overmix.
Step 5. Bake - Bake in a preheated oven at 350ºF (180ºc) for about 24 to 28 minutes or until an inserted toothpick comes out clean.
Step 6. Cool - Cool cake completely on a wire rack.
💡 Tip
Use a cake strip for a flat cake layer. If you don't have cake strips, make your own by dampening a tea towel with cold water and wrapping it around the cake pan.
How to Make Chocolate Mousse
Step 7. In a small saucepan, and off heat, whisk together heavy cream, cocoa powder, espresso powder, a whole egg, a yolk, sugar and salt until combined.
Step 9. Over low heat, and whisking constantly, heat until the mixture reaches 170ºF (76ºC).
Step 10. Off heat, add chocolate and vanilla and whisk until smooth.
Step 11. Chill the chocolate mousse mixture in the fridge for 1 hour, until thick and spreadable.
Step 12. In a large mixing bowl, and using a hand mixer, whip cold heavy cream until firm peaks. Then in 2 additions, fold spreadable chocolate mixture with whipped cream until there are no more white streaks.
Step 13. Assemble - Place cooled chocolate cake back into the springform pan. Wrap the sides of the cake with a cake collar or parchment paper. Then spread the chocolate mousse over the cake. Chill for at least 8 hours.
💡 Tip
Please note that a cake collar (acetate sheet) will give you cleaner sides. If you are using parchment paper, lightly spray it with oil to help the mousse release more easily.
Step 14. Serve - When ready to serve, pour chocolate ganache on top of the cake. Slice and enjoy!
Substitutions
For the Cake 🍰
- Sour Cream - You can easily replace with full-fat Greek yogurt.
- Neutral Oil - You can use avocado oil, vegetable oil, canola oil, refined coconut oil or grapeseed oil.
- Fine Espresso Powder - Highly recommended, but you can omit completely if don't have any in your pantry. Or you can use hot coffee inplace of hot water.
- Boiling Hot Water - You can also use hot coffee.
For the Mousse 🍫
- Fine Espresso Powder - Again, if you don't have any on-hand, you can omit it.
- Dark Chocolate Chips - I'm using Ghiradelli 60% chocolate chips, but you can also use a chocolate bar.
Storage
- Refrigerator - Store covered in the fridge for up to 5 days.
- Freezer - Wrap individual cake slices in plastic wrap. Once completely frozen, store in freezer bags. Thaw in the fridge overnight or at room temperature before consuming.
⭐️ Expert Tips
Use a kitchen scale to weigh all your ingredients. Baking in grams, rather than volume, is the best and most accurate way to bake! All my recipes include gram conversions based on King Arthur's Weight Chart.
Use a cake strip for a flat cake layer. If you don't have cake strips, make your own by dampening a tea towel with cold water and wrapping it around the cake pan.
When cooking the eggs for the chocolate mousse, cook it slow and low and whisk continuously. This will prevent you from scrambling the eggs and will ensure a smooth mixture.
FAQ
Absolutely! Bake your cake in a regular 9-inch (23cm) pan. Place your cooled cake on a serving platter and then wrap the cake with a long sheet of acetate (aka cake colar). It will be sturdy enough without needing to assemble in a pan.
Yes, you can use the mousse recipe from my no-bake chocolate mousse bars. It's egg-free and does not contain any gelatine.
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📖 Recipe
Dark Chocolate Mousse Cake
INGREDIENTS
Chocolate Cake
- 1 Cup (120g) All-Purpose Flour
- ½ Cup (42g) Dutch Cocoa Powder
- 1 Teaspoon Fine Espresso Powder (optional)
- ¾ Teaspoon Baking Powder
- ½ Teaspoon Baking Soda
- ¼ Teaspoon Fine Sea Salt
- ¾ Cup + 2 Tablespoons (175g) White Granulated Sugar
- ⅓ Cup + 1 Tablespoon (80g) Neutral Oil (avocado, vegetable, canola)
- ⅓ Cup (76g) Full-Fat Sour Cream room temp
- 1 Whole Large Egg room temp
- 1 Teaspoon Pure Vanilla Extract
- ½ Cup (113g) Boiling Water
Chocolate Mousse
- 1 ½ Cups (340g) Heavy Cream
- 1 Whole Large Egg + 1 Large Yolk
- ⅓ Cup (67g) White Granulated Sugar
- ¼ Cup (21g) Dutch Cocoa Powder
- 1 Teaspoon Fine Espresso Powder
- ⅛ Teaspoon Fine Sea Salt
- 6 Ounces (170g) Dark Chocolate
- 1 Teaspoon Pure Vanilla Extract
- 1 Cup (227g) Heavy Cream (to be whipped) cold
Chocolate Ganache
- 5 Ounces (141g) Dark Chocolate 60% to 70%
- ⅔ Cup (151g) Heavy Cream
Instructions
Chocolate Cake
- Preheat Oven & Prep Pan - Preheat oven to 350ºF (180ºC). Grease and line a 9-inch (23cm) springform pan with parchment paper.
- Combine Dry Ingredients - In a small mixing bowl, whisk together the flour, Dutch cocoa powder, fine espresso powder, baking powder, baking soda, and salt.1 Cup (120g) All-Purpose Flour½ Cup (42g) Dutch Cocoa Powder1 Teaspoon Fine Espresso Powder (optional) ¾ Teaspoon Baking Powder½ Teaspoon Baking Soda¼ Teaspoon Fine Sea Salt
- Combine Wet Ingredients - In a large bowl and using a hand whisk, whisk together sugar, oil, sour cream, egg and vanilla until well combined.¾ Cup + 2 Tablespoons (175g) White Granulated Sugar⅓ Cup + 1 Tablespoon (80g) Neutral Oil (avocado, vegetable, canola)⅓ Cup (76g) Full-Fat Sour Cream1 Whole Large Egg1 Teaspoon Pure Vanilla Extract
- Combine Dry & Wet Ingredients - Sift in the dry ingredients, ensuring the cocoa powder lumps are push through the sieve. Gently whisk the dry and wet ingredients together until nearly incorporated. The batter will be thick at this point and that's okay.
- Add Hot Water - Add boiling hot water and gently whisk until just combined. The batter will thin out a bit. Do not overmix.½ Cup (113g) Boiling Water
- Bake - Pour cake batter into your prepared pan and bake for 24 to 28 minutes or until an inserted toothpick comes out clean. Timing can vary on your oven, so keep an eye on it.
- Cool - Cool on a wire rack for 15 minutes, then remove the cake from the pan and let cool completely at room temperature or in the fridge.
Chocolate Mousse
- Combine Ingredients - In a small saucepan, and off heat, whisk together heavy cream, a whole egg, a yolk, sugar, cocoa powder, espresso powder, and salt until well combined.1 ½ Cups (340g) Heavy Cream1 Whole Large Egg + 1 Large Yolk⅓ Cup (67g) White Granulated Sugar¼ Cup (21g) Dutch Cocoa Powder1 Teaspoon Fine Espresso Powder⅛ Teaspoon Fine Sea Salt
- Cook - Over low heat, and whisking constantly, heat until the mixture reaches 170ºF (76ºC). It will take about 8 to 10 minutes.
- Add Chocolate - Off heat, add chocolate and vanilla and whisk until smooth and combined.6 Ounces (170g) Dark Chocolate 1 Teaspoon Pure Vanilla Extract
- Chill - Transfer chocolate mixture to a medium bowl and place a piece of plastic wrap directly on top to prevent a skin from forming. Chill the chocolate mousse mixture in the fridge for 1 to 1.5 hour, until thick and spreadable. If you forget and the chocolate mixture hardens, let it sit on the counter until it softens a bit.
- Prep Cake Pan - As the chocolate mousse is cooling, line the bottom of your springform pan with a fresh piece of parchment paper. If needed, level off the top of the cake with a serrated knife. Next, place cooled chocolate cake back into the springform pan. Wrap the sides of the cake with a 29-inch (74cm) long piece of acetate (cake collar). Tape the acetate together at the ends to prevent it from unraveling. You can also use parchment paper. Just lightly sprayed it with oil to make it easier to release the cake.
- Combine Whipped Cream & Cooled Chocolate Mixture - After 1 to 1.5 hours, remove the chocolate mixture from the fridge and give it a good mix. Once it has thickened into a spreadable consistency, whip your cream.In a large mixing bowl, and using a hand mixer, whip cold heavy cream until firm peaks. Do not overmix.1 Cup (227g) Heavy Cream (to be whipped)Then in 2 additions, gently fold the chocolate mixture and whipped cream together until there are no more white streaks. Do not overmix.
- Chill the Cake - Spread the chocolate mousse on top of the cake layer. Chill for at least 8 hours.
Chocolate Ganache
- When you're ready to serve, make the chocolate ganache. Place finely chopped chocolate from a bar or chocolate chips in a heatproof medium bowl. 5 Ounces (141g) Dark Chocolate 60% to 70%
- In a small saucepan, and over medium heat, bring heavy cream to a low simmer until it reaches about 185ºF (85ºC). Submerge hot cream over the chocolate and let stand untouched for 4 to 5 minutes. Using a silicone spatula, slowly stir until smooth and combined. If the chocolate hasn't completely melted, place the bowl of ganache over a small pot of simmering water. Heat until completely smooth.⅔ Cup (151g) Heavy Cream
- Remove the chilled cake from the fridge and unmold it from the pan. Peel off the acetate/parchment paper and then slide the cake onto a serving plate.
- Pour the chocolate ganache on top the cake and using an offset spatula, spread it to the edges. Before serving, you can place the cake back into the fridge for 10 to 15 minutes to let the ganache set. Slice and enjoy!!
Notes
Dani says
My husband requested this for his birthday and it did not disappoint! The mousse filling is excellent and the perfect ratio to the cake. I have a feeling we will be making this often. Thank you
Lisa Flinn says
Aww, I love hearing that, Dani! Thank you for making me a part of your celebration! 🎉
Yuni says
Tried this recipe and when I tell you my mouth was blessed I mean blessed. The ingredients were easy to find and it’s easy too make I’ve never tried chocolate moose before and I’ll make it again with this recipe keep up the good work!!!
Lisa Flinn says
Hi Yuni, thank you so much for trying the recipe and for your kind words! I'm so happy you loved it! Happy baking! ❤️
Samantha Fenech says
Can I use coconut oil ?
Lisa Flinn says
Hi Samantha, you sure can! Make sure to melt it if it has solidified. Use refined coconut oil if you want the taste to be neutral. If you only have unrefined, that works too, but you may taste the coconut flavor. Happy baking!
Marie says
This recipe is amazing with all the beautiful layers and intense chocolate taste. I will definitely make it again. Thank you
Lisa Flinn says
I'm so happy to hear you enjoyed the cake, Marie! It's one of my favorites! Thank you for making the recipe! 😊
Ciera says
Moist, decadent, chocolatey and dreamy. Will be making again for Valentine's Day.
Lisa Flinn says
I'm so happy to hear that, Ciera! It really is so dreamy! Thank you for your wonderful review! 😊
Carol says
This is just the most decadent chocolate cake but made simple. I could eat it every day, I am sure. Heaven on a plate!
Lisa Flinn says
Isn't it just the best!? Thanks so much for trying the recipe and for your wonderful review, Carol! ☺️
Meg says
My cake sunk a little bit in the middle when i removed it from the oven but otherwise it all went very well, great instructions and I'm excited to serve it! Thanks~
Lisa Flinn says
Hi Meg! I'm so happy to hear everything went well despite the cake sinking a bit. I hope you enjoy it! 🤎