This gluten free chocolate mousse cake is the perfect moist, rich chocolate cake topped with light, eggless chocolate mousse. A showstopper!
We began this decadent chocolate mousse cake with our recipe for one bowl gluten free chocolate cake. That’s one of the 10 best gluten free chocolate cakes, and there was no reason to reinvent the wheel.
But there was still the matter of the chocolate mousse. I’ve made chocolate mousse the traditional way, with raw egg whites and it’s classic and delicious.
But this time I made it with whipped cream in place of egg whites. You really just need the lift to help the chocolate mousse rise high and hold its shape on top of the rich chocolate cake.
See for yourself, my friends. Rich, chocolatey and decadent. No doubt about it.
How to make a clean mousse-topped chocolate cake
To make a beautiful layered cake like this, an acetate cake collar is really ideal. You can buy them online at Amazon.com and at most kitchen supply stores.
But if you don’t have one, you can fashion one from aluminum foil (heavy-duty works best). Just spray the inside of the collar with cooking spray so that the mousse doesn’t stick to it. It’s really quite easy, and you can make the cake way ahead of time.
C’mon. You know you want to impress the pants off of everyone at your next gathering. Go for it!
1/2 teaspoon xanthan gum (omit if your blend already contains it)
11 tablespoons (55 g) unsweetened cocoa powder (I prefer Dutch-processed in this recipe, but made it with natural cocoa powder and it worked fine)
3/8 teaspoon kosher salt
3/8 teaspoon baking soda
3/4 cup (150 g) sugar
1/2 cup + 1 tablespoon (126 g) sour cream, at room temperature
6 tablespoons (84 g) vegetable oil
1 egg + 1 egg yolk (90 g, out of shell) at room temperature, beaten
1/2 cup + 1 tablespoon (4 1/2 ounces) warm water (about 95°F)
CHOCOLATE MOUSSE 1/4 cup (20 g) unsweetened cocoa powder (Dutch-processed is best, but natural will work, too)
1/2 cup (4 ounces) warm water
10 ounces dark chocolate, chopped
4 tablespoons (56 g) unsalted butter, chopped
2 cups (16 fluid ounces) heavy whipping cream
1/4 cup (29 g) confectioners’ sugar
Preheat your oven to 350°F. Grease an 8-inch round (or springform) baking pan and set it aside. I did not bake my chocolate cake in a springform pan, but did assemble the chocolate cake in one.
Make the cake. In a large bowl, place the flour, xanthan gum, cocoa powder, salt, baking soda and sugar, and whisk to combine well. Create a well in the center of the dry ingredients and add the sour cream, oil, eggs and water, mixing to combine after each addition. The batter should be very thickly pourable. Scrape the batter into the prepared pan, smooth into an even layer and place in the center of the preheated oven. Bake until a toothpick inserted in the center of the cake comes out mostly clean or with a few moist crumbs attached (about 30 minutes). Do not overbake. Remove from the oven and allow to cool for 10 minutes in the pan before inverting onto a wire rack to cool completely.
While the cake is cooling, make the chocolate mousse. In a small bowl, whisk the cocoa powder into the warm water until it dissolves completely. Set it aside. In a small, heat-safe bowl, place the chopped chocolate and chopped butter, and place over a small saucepan of simmering water, making sure the bowl does not touch the water. Melt the chocolate and butter over the simmering water, stirring occasionally, until smooth. Alternatively, you can melt them together in the microwave in short, 30-second bursts, stirring well in between. Remove the melted chocolate and butter, and whisk the cocoa powder dissolved in water into it until smooth. Set the bowl aside. In the bowl of a stand mixer fitted with the whisk attachment, or in a large bowl with a hand mixer, whip the heavy whipping cream on medium-high speed until soft peaks form. Add the confectioners’ sugar, and whip again until stiff, shiny peaks form. Pour the chocolate mixture into the bowl of whipped cream slowly, carefully folding the ingredients together and taking care not to deflate the whipped cream more than necessary. Fold until no white streaks remain.
Assemble the cake. To assemble the cake, you will need a springform pan and either a 4-inch tall acetate cake collar (like you see in the photos) or one fashioned out of aluminum foil, with the inside sprayed with cooking oil to prevent the mousse from sticking to it. First, cover the base of the springform pan tightly with plastic wrap, and place the inverted cake on top of the base. Trim the edges of the cake with a sharp knife if necessary to fit it inside the lip of the base of the pan. Fit your cake collar around the cake(or makeshift cake collar), then clip the sides of the springform pan to the base to enclose the cake and collar. Spoon the chocolate mousse onto the enclosed cake, and smooth the top. Refrigerate the cake until the chocolate mousse is set (about 2 hours). Slice and serve chilled.