Chocolate Mousse Cake
You have found the chocolate cake that ends all chocolate cakes! This incredible dessert is chocolate HEAVEN, designed for chocolate purists, chocoholics, chocolate addicts... whatever you want to call us! My Chocolate Mousse Cake is outrageously decadent and delicious with rich, moist chocolate cake topped with a thick layer of dark chocolate mousse. As decadent as it is, it is also so light and airy. The best part is how easy this recipe is with a simple one bowl cake batter and no fuss chocolate mousse that doesn't contain any raw egg. You will impress anyone you serve this too, and you'll feel like a star since it's not that hard. If you love chocolate cake, make sure you check out my Best Moist Chocolate Cake, One Bowl Chocolate Sheet Cake and Ultimate Moist Chocolate Fudge Cake.
WHY THIS RECIPE WORKS
- Easy to make - the chocolate cake batter is so simple. You just mix all of the ingredients in one bowl and bake.
- Super moist chocolate cake - the cake is super moist! It has a soft texture and fine crumb that stays moist for days without drying out, and it is even moist when cold from the fridge as necessary since this cake should be stored chilled.
- Rises flat - this cake rises nice and even so you have a flat surface to layer on the mousse which makes for easy preparation and clean presentation.
- Light and airy chocolate mousse - you will find the texture of this chocolate mousse to be irresistible as it melts in your mouth.
- Rich chocolate flavor - both the cake and mousse have a smooth and rich chocolate taste.
INGREDIENTS FOR CHOCOLATE MOUSSE CAKE
Here are some notes about the ingredients. For a full list of ingredients, check out the recipe card at the bottom of the page.
- All purpose flour - you do not need specialty cake flour to make a wonderful chocolate cake. Just be sure to measure your flour correctly. Adding too much flour is the most common mistake and leads to tough and dry cake. The most accurate way to measure flour is using a scale. If you don't have one then fluff your flour with a spoon, spoon it into your measuring cup and use a knife to level it off. This batter is meant to be thin so refrain from adding more flour to make it thicker.
- Granulated sugar - simple white sugar will keep this cake moist and tender.
- Pure vanilla extract - vanilla is important to enhance the flavor of chocolate.
- Cocoa powder - I recommend getting some good quality cocoa powder. It's the main flavor and you want it to shine so use the best you can find. I love to use this Dutch Process cocoa powder for this recipe. Make sure you use unsweetened cocoa powder and not cocoa mix.
- Eggs - one whole egg will set the structure of this cake and help emulsify the batter. You'll also need 3 egg yolks for the mousse.
- Oil - this is an oil-based cake because oil is liquid at room temperature (it's an unsaturated fat) which means that the cake will still be soft when it's cold.
- Sour cream - one of the secrets to this moist chocolate cake is sour cream! It contributes the dairy undertones, rich flavor and body (thanks to its high protein and fat content) that oil-based cakes lack. Full fat sour cream adds richness and dairy notes to this cake in the absence of butter.
- Milk - you'll need milk for the cake batter and also for the chocolate mousse layer. It forms the base of the custard for the mousse and I recommend whole milk.
- Dark chocolate - you'll need pure dark chocolate to make the chocolate mousse. Anything between 50 and 70% cocoa solids will work, but I highly recommend dark chocolate with 60% cocoa solids. You can blend semisweet chocolate with my favorite bittersweet chocolate callets which are very convenient.
- Milk chocolate - a bit of milk chocolate contributes additional milk solids for more body.
- Whipping cream - look for whipping cream or "heavy" cream with 35% milkfat to make the chocolate mousse truffle layer and the chocolate ganache glaze.
STEP BY STEP INSTRUCTIONS: HOW TO MAKE CHOCOLATE MOUSSE CAKE
- STEP 1). Make the cake base. Combine dry ingredients. Sift flour, cocoa powder, baking powder and baking soda into a medium bowl. Add sugar and salt, then whisk to blend evenly.
- STEP 2). Add wet ingredients. Make a well in the center of the dry ingredients, then add oil, beaten egg, sour cream, milk and vanilla extract and slowly whisk it in until combined and the batter is smooth.
- STEP 3). Bake. Spread batter evenly into prepared pan using a small offset spatula and bake for 20-25 minutes until a skewer inserted into the center comes out clean. Transfer to a wire rack and let cool completely in the pan. Trim the top of the cake to level it out and make it flat if necessary, but I never need to because it always bakes up nice and flat.
- STEP 4). Make the mousse. Place finely chopped dark chocolate and milk chocolate in a medium heatproof bowl and set aside. Place the milk in a heatproof measuring jug and microwave until steaming. You can also heat it in a saucepan but be sure to cover the pot so you don't loose too much water through evaporation.
- STEP 5). Make custard. Combine egg yolks and sugar in a 1 quart stainless steel saucepan (this is my go-to pouring saucepan that everyone asks me about) and whisk until smooth and evenly blended. Very slowly pour in the milk while whisking until it is all combined. Transfer the pot to the stove and stir constantly using a rubber spatula or wooden spoon over medium-low heat for 5-7 minutes until it thickens. It should coat the back of a spoon like thick cream. Immediately pour the hot custard over the chocolate, add salt and stir until smooth and the chocolate is completely melted. If necessary, (like if it is cold in your house) place the bowl in the microwave and heat on low power for just 20-30 seconds to melt any residual pieces of chocolate. Let cool for about 10-15 minutes so it is no longer hot.
- STEP 6). Fold in cream. Place cold cream in a medium bowl and use an electric hand mixer to whip to medium peaks which is somewhere between soft and stiff peaks. When you lift the beaters, the cream chocolate curl just slightly when it reaches this stage. Take one third of the whipped cream and fold it evenly into the chocolate custard to lighten it up. You don't need to be too gentle at this first stage. Gently fold in the remaining cream in 2 stages being careful not to deflate the air. Watch the video tutorial to see the folding technique I use.
- STEP 7). Assemble the cake. Spoon the mousse over the cooled cake still in the pan and spread it out evenly using a small offset spatula. Place it in the fridge for at least 4 hours to set.
WHAT IS THE DIFFERENCE BETWEEN DUTCH COCOA POWDER AND NATURAL COCOA POWDER?
- Dutch cocoa powder is cocoa powder that has been treated with an alkalizing agent (a basic ingredient) such as potassium carbonate or sodium carbonate. This treatment, combined with certain parameters of pressure and temperature will increase the pH (decrease the acidity) of the cocoa powder to give it a less sour taste, darken the color and help it become more dispersible in water. My preferences for Dutch cocoa powder ones with a higher fat content and they are this Cacao Barry Extra Brute, Ghirardelli Majestic and Green & Blacks Organic.
- Natural cocoa has not been alkalized and is 100% cocoa powder. It has a lighter color and has a very lovely fruity flavor with some pleasant acidity and slight bitterness that is inherent to the cocoa bean. My preferences for natural cocoa are Ghirardelli 100% Cocoa and Hershey's Unsweetened.
WHAT IS CHOCOLATE MOUSSE?
Chocolate mousse is a classic French dessert that doesn't require any baking. It is a rich dish traditionally prepared with raw eggs by first blending melted chocolate with butter or water and stirring in egg yolks. The dense chocolate mixture is lightened up by folding in whipped egg whites and/or whipped cream. My recipe for chocolate mousse does not have raw eggs so it is acceptable for anyone to consume. I prepare it by first making a custard with egg yolks, sugar and milk, then mixing in chocolate while it is hot so it melts. I fold in cold whipped cream instead of raw egg whites and the result is fluffy, airy and so creamy.
EXPERT BAKING TIPS
- Use a neutral tasting oil like pure sunflower oil for the cleanest flavor to let the chocolate taste stand out.
- Do not reduce the sugar. The right amount of sugar will make cake moist because it binds water so that it stays tightly in the batter and doesn't evaporate excessively during baking. The right amount of sugar keeps the cake tender even when served cold.
- Keep an eye on the baking time. Set a timer for the first time stated in the recipe and check with a skewer - it should come out clean.
- Stir the ganache gently. Do not whip the cream and chocolate when making the ganache for the truffle layer or it will cause the milkfat and the cocoa butter to separate.
- Whip the cream just to soft peaks. This will create a delicate soft truffle filling. If you over-whip the cream, it may give the mousse a grainy texture.
RECIPE FAQ
Firstly - use a fresh oil! Do not use anything that's been opened for a long time and when you store oil, it should be in a cool dark place. Light and heat accelerate oxidation reactions that can make the flavor turn rancid. My oil of choice for baking is sunflower oil for its clean and neutral taste, but any other oil such as canola or safflower will do. You can even use olive oil, but keep in mind that it will add the taste of olive oil to the cake.
This recipe works with both Dutch process and natural cocoa powder. For a darker color like in this photo, I use high fat Dutch cocoa powder. My absolute preference is this one and this one. The first one is rich with a deep color while still having some nice complex fruity notes which some Dutch cocoa powders can lack. Natural cocoa has a wonderful fruity flavor and I like to use it as well. You can use Hershey's natural cocoa or this one that I love.
Sour cream really makes this cake delicious, but if sour cream is not available to you where you live, you can also make this recipe using an equal amount of full fat Greek yogurt. I have tested this and it worked well! Another suitable substitution is crème fraîche which is a type of fermented dairy product somewhere between yogurt and sour cream.
It's not more fat! Moisture comes from liquid, not fat. So you can add more butter and more oil, but it will really just make the cake more dense and more tender by shortening the texture. Fat will not make a cake moist as only liquids can add moisture. This cake is moist because of the amount of liquid.
I normally scoff at a cake recipe that uses only oil and no butter since butter is superior for its flavor. However, oil makes the texture very soft and in turn gives the perception of "moistness". That's because oil is made up of mostly unsaturated fats that are liquid at room temperature. Butter contains more saturated fats that are solid at room temperature, therefore the texture of a butter cake will be more crumbly and firm.
Yes, you can make this cake in a 9-inch round pan. If you use an 8-inch round pan the cake and mousse layers will be taller and the cake will take longer to bake. If you use a 9x9-inch square pan, the cake layer and the truffle layer will be thinner.
If you want an extra thick and tall chocolate mousse layer, you can double all of the quantities. The only difference is that it will take slightly longer to chill and you may want to use an acetate strip to hold it in.
I would not recommend freezing this whole cake as the mousse topping will have a very different texture once thawed. However, you can freeze the cooled cake base. Just wrap it well in plastic and then store in a freezer bag in the freezer for up to 3 months.
If you love cake, check out these recipes!
Ultimate Moist Chocolate Fudge Cake Lemon Pistachio Cake Sticky Toffee Date Cake Moist Lemon Blueberry Bread Olive Oil Chocolate Bundt Cake Best Vanilla Cupcake Recipe with Chocolate Fudge Frosting Chocolate Chip Banana Cake with Creamy Milk Chocolate Frosting Blueberry Peach Upside Down CakeFor the love of chocolate
Looking for more decadent chocolate recipes? Try these:
More chocolate cake
Here are more delicious chocolate cake recipes:
Video
Chocolate Mousse Cake
Ingredients
Chocolate Cake Batter:
- ⅔ cup (95g) all-purpose flour
- ⅓ cup (28g) cocoa powder (I prefer this one)
- ½ teaspoon baking powder
- ¼ teaspoon baking soda
- ¾ cup (150g) granulated sugar
- ¼ teaspoon salt
- ¼ cup (60ml) sunflower oil
- 1 large egg, lightly beaten
- ¼ cup (60ml) full fat sour cream
- ⅓ cup (80ml) warm milk
- 1 teaspoon (5ml) pure vanilla extract
Chocolate Mousse:
- 5 oz (142g) bittersweet chocolate (70% cocoa), finely chopped
- 2 oz (56g) milk chocolate, finely chopped
- ⅔ cup (150ml) whole milk
- 3 large egg yolks
- ⅓ cup (65g) granulated sugar
- pinch of salt
- 1 ¼ cups (300ml) cold heavy 35% whipping cream
NOTE: for best results, use a kitchen scale to weigh the ingredients.
Instructions
- Preheat the oven to 350°F. Line an 8x8-inch metal baking pan with parchment paper leaving a 2-inch overhang at each side so you can easily remove the cake afterwards.
- Make the cake. Sift flour, cocoa powder, baking powder and baking soda into a medium bowl. Add sugar and salt, then whisk to blend evenly.
- Make a well in the center of the dry ingredients, then add oil, beaten egg, sour cream, milk and vanilla extract and slowly whisk it in until combined and the batter is smooth.
- Spread batter evenly into prepared pan using a small offset spatula and bake for 20-25 minutes until a skewer inserted into the center comes out clean. Transfer to a wire rack and let cool completely in the pan. Trim the top of the cake to level it out and make it flat if necessary, but I never need to because it always bakes up nice and flat.
- Make the mousse. Place finely chopped dark chocolate and milk chocolate in a medium heatproof bowl and set aside.
- Place the milk in a heatproof measuring jug and microwave for 45-60 seconds until steaming. You can also heat it in a saucepan but be sure to cover the pot so you don't loose too much water through evaporation.
- Combine egg yolks and sugar in a 1 quart stainless steel saucepan (this is my go-to pouring saucepan that everyone asks me about) and whisk until smooth and evenly blended. Very slowly pour in the warm milk while whisking until it is all combined. Transfer the pot to the stove and stir constantly using a rubber spatula or wooden spoon over medium-low heat for 5-7 minutes until it thickens. It should coat the back of a spoon like thick cream. Immediately pour the hot custard over the chocolate, add salt and stir until smooth and the chocolate is completely melted. If necessary, (like if it is cold in your house) place the bowl in the microwave and heat on low power for just 20-30 seconds to melt any residual pieces of chocolate. Let cool for about 10-15 minutes so it is no longer hot.
- Place cold cream in a medium bowl and use an electric hand mixer to whip to medium peaks which is somewhere between soft and stiff peaks. When you lift the beaters, the cream chocolate curl just slightly when it reaches this stage. Take one third of the whipped cream and fold it evenly into the chocolate custard to lighten it up. You don't need to be too gentle at this first stage. Gently fold in the remaining cream in 2 stages being careful not to deflate the air. Watch the video tutorial to see the folding technique I use.
- Spoon the mousse over the cooled cake still in the pan and spread it out evenly using a small offset spatula. Place it in the fridge for at least 4 hours to set.
- When you're ready to serve, use a small offset spatula to release the sides of the cake/mousse from the pan where you have no parchment, then use the parchment overhang to lift it out of the pan. Sift cocoa powder over the top before slicing and serving.
Just letting you know that I made this for my friend for lunch yesterday. I served it with quenelles of crushed raspberries folded through softly whipped cream. I used 25% Lindt milk chocolate and 75%, Lidnt 70% chocolate as we prefer it less bitter. The results were spectacular. The cake base is light and chocolatey and mousse is also light though full flavoured. Quite a success and one to have in your arsenal. It does take time to make but I made it 2 days in advance, refrigerated and it was perfect on the day. I have frozen the remaining half for a tea I am doing next week ! Well done and thank you for the recipe.
You are welcome Charlotte! Glad it was a success 🙂
I made this as dessert for a graduation party that was already stressing me out and it was a hit! I have to admit I just used chocolate chips and a milk chocolate bar from Trader Joe’s, but I imagine it would be even better with specialty chocolate. I put some instant espresso powder in the cake batter, and served with fresh sliced strawberries. Perfect and it cut so cleanly when I ran my knife under hot water (and dried it) before slicing. The 8 inch pan yielded 12 generous slices.
Thanks for the feedback Megan! Glad it was a success 🙂