When you want a truly decadent dessert, look no further than this Keto Chocolate Mousse Cake. It is a chocoholic’s dream with three heavenly layers. It starts with a layer of tender coconut flour cake that’s piled high with keto chocolate mousse. Then it’s all topped off with a luscious chocolate ganache. It looks and tastes like it came from an expensive bakery!
Keto dessert that’s worth the effort
Baking is a state of mind, and it requires patience and attention to detail. Over the years, I’ve learned that if I am not in the mood or I am in a hurry, something goes awry and my results are mediocre at best. Even for recipes I’ve made dozens of times!
These days, as a solo parent running a household and a business, I often don’t have the time to relax and enjoy the process. But when I do, I love nothing more than devoting my time to creating a spectacular keto dessert that defies expectations. This keto chocolate mousse cake is my latest offering – and it is absolutely worth the time and effort.
Recipe Highlights
Nut-free chocolate cake: The base is a layer of coconut flour chocolate cake, so the whole recipe is free of nuts.
No raw eggs: I tried a new method of making chocolate mousse, in which the eggs and yolks are cooked gently in a double boiler before proceeding. It worked beautifully and resulted in a silky mousse.
Rich chocolate flavor: All layers of this gorgeous cake have deep, rich chocolate flavor that simply melt in your mouth.
Low carb: With only 3.8 grams net carbs, this luscious dessert won’t derail your keto or low carb diet!
Ingredients and Substitutions
- Coconut flour: I used a half recipe of my keto chocolate cupcakes for the cake base. See the Frequently Asked Questions if you would prefer to use almond flour.
- Cocoa powder: I always use Dutch process for a richer chocolate flavor.
- Sweetener: I use a mix of both erythritol- and allulose-based to get the best results. Please see the Sweetener Options section for more information.
- Protein powder: As always, a little protein powder helps the cake rise a little better. Egg white protein powder works as well.
- Eggs: You will need three eggs for the cake, as well as one egg and two egg yolks for the mousse.
- Whipping cream: This is used in both the mousse and the chocolate ganache topping.
- Unsweetened chocolate: Do not use sugar-free chocolate (i.e. Lily’s, ChocZero, or an equivalent), as it will not create the right structure for the mousse or the ganache. Use only 100% unsweetened chocolate.
- Baking staples: Oil, baking powder, salt, vanilla extract.
How to Make Keto Chocolate Mousse Cake
- Prepare the cake layer: Whisk together the dry ingredients, then stir in the wet ingredients. Pour the batter into an 8-inch pan with a removable bottom and bake 15 to 20 minutes.
- Heat the eggs: Combine the egg, egg yolks, allulose, and some of the cream in a heatproof bowl over a pan of barely simmering water. Whisk continuously until the mixture reaches 160ºF. Remove from heat and add the chocolate.
- Whip the cream: Beat the remaining cream with the sweetener until it holds stiff peaks. Gently fold into the chocolate mixture.
- Freeze the cake: Spread the mousse over the cooled cake. Place the whole pan in the freezer until firm. Run a sharp knife around the inside of the pan and remove the sides.
- Make the ganache: Bring the cream and sweetener to a simmer. Add the chocolate and whisk until smooth.
- Pour over the cake: Pour the ganache over the top of the cake, allowing it to drip down the sides.
Carolyn’s Tips for Success
Bake the cake only until it is just firm to the touch on top. Watch it carefully, as baking it too long will cause it to be quite dry.
Let the cake layer cool properly before adding the mousse filling. If it is still warm, it will melt the mousse and the cake won’t set properly.
When bringing the egg mixture up to temperature, be sure to keep the heat very low and whisk constantly to avoid curdling. Test the temperature frequently, and remove from heat the moment it reaches 160ºF.
To loosen the cake from the pan, I like to heat my knife up over the flame of my gas stove. You can also heat up some water in a kettle and pour it over the blade. Keep the blade tight to the sides of the pan as you run it around the cake.
Keep the cake frozen until you are ready to pour the ganache over top. This keeps the mousse from melting with the warmth of the glaze, and also helps set the topping faster.
Sweetener Options
It’s important to understand how different sweeteners will affect your results. In the cake layer, you can really use any sweetener you like best. It doesn’t bake that long, and it’s already a dark color, so allulose and xylitol work just as well as erythritol.
For the mousse, I recommend a mix of allulose and powdered erythritol. Using erythritol on its own may cause some recrystallization, whereas using only allulose will make the mousse overly soft and it may not set properly.
The ganache can work with either sweetener. I prefer allulose to avoid recrystallization. You can also use xylitol.
As always, you are free to use whatever you like, but I cannot guarantee the results if you don’t follow my recommendations.
Frequently Asked Questions
More Keto Chocolate Cakes To Love!
Keto Chocolate Mousse Cake Recipe
Equipment
Ingredients
Cake
- 1/3 cup (40 g) coconut flour
- 1/3 cup (63.33 g) granular sweetener, erythritol, allulose, or a mix
- 3 tbsp (15.22 g) cocoa powder
- 2 tbsp (21.4 g) whey protein powder, chocolate, vanilla, or unflavored
- 1 1/2 tsp baking powder
- 1/2 tsp salt
- 3 large eggs, room temperature
- 1/3 cup (78.86 ml) avocado oil
- 3/4 tsp vanilla extract
- 1/4 cup (59.15 ml) leftover coffee, or water (more as needed)
Chocolate Mousse
- 1 large egg
- 2 large egg yolks
- 3 tbsp (30.43 g) allulose, or xylitol
- Pinch salt
- 1 1/3 cup (315.45 ml) heavy whipping cream, divided
- 3 ounces (85.05 g) unsweetened chocolate, chopped
- 1/3 cup (63.33 g) powdered sweetener, erythritol recommended
- 1 tsp vanilla extract
Chocolate Ganache
- 1/3 cup (78.86 ml) heavy whipping cream
- 3 tbsp (30.43 g) sweetener, erythritol, allulose, or a mix
- 1 1/2 ounces (42.52 g) unsweetened chocolate, chopped
- 1/2 tsp vanilla extract
Instructions
Cake
- Preheat the oven to 325ºF and lightly grease an 8-inch round cake pan with a removable bottom (or a springform pan). Line the bottom with a circle of parchment and grease the parchment.
- In a large bowl, whisk together the coconut flour, sweetener, cocoa powder, protein powder, baking powder, and salt. Stir in the eggs, oil, and vanilla extract until well combined.
- Stir in the coffee a little at a time until the batter is thick but easily scoopable.
- Spread in the prepared pan and smooth the top. Bake 15 to 20 minutes, or until the top is just firm to the touch. Remove and let cool completely in the pan, then run a sharp knife around the inside of the pan to loosen the cake.
Chocolate Mousse
- In a heatproof bowl set over a pan of barely simmering water, combine the egg, egg yolks, allulose, and salt. Whisk to combine well, then whisk in 1/3 cup of the heavy cream.
- Continue to whisk continuously until the mixture becomes frothy, thicker, and lighter in color. To be safe, it should read 160ºF on an instant read thermometer.
- Remove the bowl from over the pan and add the chopped chocolate. Let sit 5 minutes to melt and then whisk until smooth. Set aside to cool to room temperature.
- In a large bowl, beat the remaining 1 cup of heavy cream with the powdered sweetener and the vanilla until it holds stiff peaks. Gently fold the whipped cream into the chocolate mixture in 3 additions.
- Spread the mousse over the cake in the pan, making sure to spread all the way to the edges and even out the top. Freeze until firm.
- Heat up a sharp knife and run it around the inside of the pan to loosen the cake. Push up from the bottom (or loosen the sides, if using a springform pan), and remove the cake from the pan. Keep chilled while preparing the topping.
Chocolate Ganache
- In a small saucepan over medium heat, whisk together the cream and sweetener. Bring to a simmer.
- Remove from heat and add the chocolate and vanilla. Let sit a few minutes to melt the chocolate and then whisk until smooth.
- Pour over the top of the cake, allowing some to drip down the sides. Refrigerate for 20 minutes to set the topping.
Notes
Nutrition
Nutritional Disclaimer
Please note that I am not a medical or nutritional professional. I am simply recounting and sharing my own experiences on this blog. Nothing I express here should be taken as medical advice and you should consult with your doctor before starting any diet or exercise program. I provide nutritional information for my recipes simply as a courtesy to my readers. It is calculated using MacGourmet software and I remove erythritol from the final carb count and net carb count, as it does not affect my own blood glucose levels. I do my best to be as accurate as possible but you should independently calculate nutritional information on your own before relying on them. I expressly disclaim any and all liability of any kind with respect to any act or omission wholly or in part in reliance on anything contained in this website.
Free Bonus: Secrets to Keto Baking!
Sign up for your favorite recipes delivered straight to your inbox plus get our FREE bonus: Secrets to Keto Baking!
