Triple Chocolate Mousse Cake

After sharing several of our recent sweet treats on the blog, we’ve received dessert requests from multiple friends and family members! What better way to combine our love for baking and experimenting with complex recipes than by making custom creations for people we love! This weekend, we were asked to make a chocolate dessert for a good friend's dinner party to celebrate the end of the school year. We wanted to give them a decadent and elegant treat, and after browsing through many recipes, we found this incredible recipe from Cooks Illustrated and were up for the challenge. 

This Triple Chocolate Mousse Cake combines a dense, flourless chocolate cake layer with two layers of airy chocolate mousse, making for a rich yet not overpowering sweetness. The entire cake is assembled in a springform pan, where the bottom cake layer is first baked and later topped with the two mousse layers after cooling. 

When buying our ingredients, we made sure to do our research to use the most highly reviewed chocolate for baking. After reading an article on The Best Baking Chocolate from Real Simple, we found that Trader Joe’s Pound Plus 72% Dark won for the best bittersweet chocolate, and that Ghirardelli Classic White Chips won for the best white chocolate! We couldn’t be happier that both these brands are available in stores nearby.

As the recipe suggests, this cake is best served after being chilled for at least 2.5 hours, so the mousse layers have plenty of time to set. It can even be made a day in advance and refrigerated, however should then be left out at room temperature for about 45 minutes before serving. 

We were happy to see that the crowd was very pleased with how our cake turned out; there were lots of empty plates and full bellies and just one piece of cake left when the night was over. We have already received requests to make this cake again in the near future, and will be saving this recipe in our collection of successes! Thanks to Cook’s Illustrated for doing all the hard work for us! 

Triple Chocolate Mousse Cake
Recipe by Cook's Illustrated

Ingredients

• 6 tablespoons unsalted butter, cut into 6 pieces
• 7 ounces finely chopped bittersweet chocolate, for bottom layer
• 1 1/2 teaspoons vanilla extract
• 4 eggs, separated
• 1/3 cup light brown sugar, packed
• 2 tablespoons cocoa powder, preferably dutch processed
• 5 tablespoons hot water
• 7 ounces finely chopped bittersweet chocolate, for middle layer
• 1 1/2 cups heavy cream, for middle layer
• 1 tablespoon granulated sugar
• pinch salt, for middle layer
• 3/4 teaspoon powdered gelatin
• 1 tablespoon water
• 6 ounces white chocolate chips
• 1 1/2 cups heavy cream, for top layer

Cooking Directions

1. For bottom layer
2. Preheat oven to 350 degrees F. 
3. Butter bottom and sides of a 9 inch springform pan and line bottom with parchment paper to prevent sticking. 
4. Combine butter and chocolate in a large heatproof bowl set over simmering water. Stir occasionally until mixture is smooth. Remove from heat and let cool slightly, about 5 minutes. 
5. Whisk in vanilla and egg yolks and set aside. 
6. In a stand mixer with whisk attachment, beat egg whites and salt on medium speed until foamy. Crumble half of brown sugar into mixing bowl to remove any lumps and beat until incorporated. Add remaining brown sugar and continue to beat on high until stiff peaks form. 
7. Using a whisk, beat one third of egg whites into chocolate mixture to lighten it. Gently fold in remaining egg whites with rubber spatula until no streaks remain. Pour batter into prepared springform pan and smooth top with spatula. 
8. Bake until cake has risen, is firm around edges and center has just set but is still soft (should spring back after pressing gently with a finger), 14-18 minutes. Transfer cake to wire rack to cool completely in pan, about 1 hour. 
9. For middle layer
10. Whisk together cocoa powder and water in a small bowl and set aside. 
11. Melt chocolate in a large heatproof bowl set over simmering water, stirring occasionally until smooth. Once melted, remove from heat and cool slightly, 2-5 minutes.
12. In a stand mixer with whisk attachment, whip cream, sugar and salt on medium speed until mixture begins to thicken. Increase speed to high and whip until soft peaks form. Whisk in cocoa powder mixture until smooth. 
13. Using a whisk, mix one third of the whipped cream to the chocolate mixture to lighten it. Gently fold in remaining whipped cream with rubber spatula until no streaks remain. 
14. Pour mousse into springform pan over cooled cake and tap gently on counter to remove air bubbles. Gently smooth top with a spatula and refrigerate for at least 15 minutes while preparing top layer. 
15. For top layer
16. Sprinkle gelatin over water in small bowl and let stand 5 minutes to soften. 
17. Place white chocolate chips in a medium bowl. 
18. Bring 1/2 cup of cream to boil in a small saucepan. 
19. Remove pan from heat, add gelatin mixture and stir until dissolved. 
20. Pour hot cream mixture over white chocolate chips and let stand 1 minute. Whisk until mixture is smooth and cool to room temperature, 5-8 minutes. 
21. In a stand mixer with whisk attachment, whip remaining 1 cup of cream at medium speed until it begins thickening. Increase speed to high and whip until soft peaks form. Using a whisk, mix one third of whipped cream into white chocolate mixture to lighten it. Gently fold in remaining whipped cream with rubber spatula until no streaks remain. 
22. Spoon white chocolate mousse into pan over middle layer and smooth top with spatula. 
23. Return cake into refrigerator and chill until set, at least 2 1/2 hours. 
24. Top with cocoa powder, chocolate shavings and raspberries as desired. 

Enjoy!