Chocolate Mousse Cake

IMG_2483I have always usually been outnumbered in my family by people who aren’t enamored by chocolate. Same was true when I married my husband. Even more so. But then the kids came, and they loved chocolate, especially  dark chocolate. It was then that I knew they were mine (that was the real testament, not the whole watching them come out of me thing). And so now I have little people to share my chocolate obsession with. Little people to make chocolate cake for on birthdays. Little hands to help stir the chocolate chips into cookie dough. And little fingers to steal chocolate chips from the counter before they even have a shot at meeting pancake batter.

IMG_7226 I’ve been planning on making this cake for months now. In March as I assembled my husband’s strawberry shortcake, I was actually thinking of this one. In January while I frosted my daughter’s rocket cake, I secretly fantasized about the light, airy and intensely chocolatey flavor this mousse would impart on a chocolate layer cake. But now it was my son’s birthday, and it was just the four of us. So I went the whole nine chocolate yards.

There are so many things that make this cake delicious. Chocolate, vanilla, and coffee all flavor the chocolate layers. The original recipe doesn’t call for espresso, but this girl learned from the school of Ina Garten, so there is going to be some coffee in my chocolate cake. The mousse is decadent with 2 cups of heavy cream, 13 oz of bittersweet chocolate, 7 egg whites. This is definitely not an everyday cake, but so worth the effort once you take a bite of the finished product. IMG_7227It’s also not for the novice baker, unfortunately. There is egg white beating, folding, chocolate melting, cooling, uniform cake slicing, etc. So if you’ve done these a few times, then you won’t be daunted by this recipe.

The recipe for the mousse makes 8 cups and the directions imply an even divide of all 8 cups between and atop the 3 layers. I needed much less, even when applying the mousse around the sides like a frosting. I used 6 cups for the layers, 1 cup around the sides, and 1 cup for my midnight craving =)

The only thing to be aware of is if you use it around the sides, this cake will have to be refrigerated. At room temperature, the liquid will start to separate and you’ll have a chocolatey mess for the cake. So, keep it in the fridge until just ready to slice and serve.

IMG_2480At this point I have to make a shout out to my friend Jenn Chowdhury, who gifted me this lovely antique cake stand! You might remember the vanilla cake with chocolate buttercream frosting I made for her birthday a few months back.  I’ve been in the market for a while now, since my previous one broke, and this came in the mail like a gift from above. So, thank  you Jenn!!

Recipe adapted from Fine Cooking.


For the cake

  • Butter or vegetable oil for greasing the pan
  • 1 1/2 cups cake flour
  • 6 tbsps unsweetened natural cocoa powder
  • 2 tsp baking pwder
  • 1/4 tsp baking soda
  • 1/4 tsp kosher salt
  • 1 cup white sugar
  • 1/4 cup vegetable oil
  • 1 large egg
  • 1 tsp vanilla extract
  • 1 cup hottest tap water
  • 1 tsp instant espresso

For the mousse

  • 2 cups heavy cream
  • 1/4 cup unsweetened natural cocoa
  • 13 oz bittersweet chocolate (I used Ghirardelli)
  • 2 tsp vanilla extract
  • 7 large egg whites at room temperature
  • 1/2 cup white sugar


For the cake

  1. Position a rack in the center of the oven and preheat to 325 degrees Fahrenheit.
  2. Grease a 9×2 circular cake pan. Line the bottom with parchment paper and flour the sides of the pan.
  3. Sift the cake flour, cocoa, baking powder, baking soda, and salt into a large bowl. Add the sugar and whisk until all the ingredients are well blended. Measure the oil into a liquid measuring cup. Add the egg and vanilla and mix with a fork. Add to the dry ingredients.
  4. Fill the liquid measuring cup with 1 cup hottest tap water. Dissolve the espresso in it and add to the dry ingredients. Mix until the dry ingredients  are just moist, scraping down the sides of the bowl. Pour batter into prepared pan and bake for 32 to 34 minutes (I baked for 34 min because we’re not dealing with cupcakes here; I’m not too worried about it drying out.) Test it with a toothpick, ensuring that it comes out clean.
  5. Let it cool in the pan for a bit, until you can handle it with your bare hands. Invert it onto a wire rack to cool completely. I like to loosen the sides with a metal spatula or butterknife. Then I place on hand on top, turn the cake out onto my hand, and delicately place over the wire rack. Remove the parchment paper. Let cool to room temperature. Refrigerate or freeze until ready to apply the mousse.
  6. The original recipe suggests assembling it in a springform pan, but I just did so on the cake stand. Slice the cake into three even layers. I like to cut an inch or two deep going around the circumference, before cutting all the way through (otherwise I usually end up with slanted layers). Set the top two layers aside. Scoop about 2 cups of the mousse onto the layer. Spread delicately with a spatula. Add the second cake layer on top. Scoop an additional 2 cups of mousse and spread evenly. Add the top layer and an additional 2 cups mousse. Before applying to the sides, add strips of parchment paper on the cake stand, tucking into the bottom layer (just to keep the surface clean). Starting from the top, add a dollop of mousse and carefully push down the sides. Rotate the stand and continue until the sides are fully covered.
  7. Garnish with chocolate curls, if desired. Refrigerate until ready to be eaten.

For the mousse

  1. Set up an ice bath in a large bowl. Bring the cream and cocoa to a boil in a large saucepan over medium heat, whisking to incorporate all the cocoa. Remove from heat and add the chopped chocolate and butter. Whisk until well combined. Pour the chocolate mixture into a medium bowl and place over ice bath. Keep stirring while the mixture comes to room temperature. Remove bowl from ice bath.
  2. Beat the egg whites in a large bowl with a hand held electric mixture on low speed until frothy. Increase speed to medium and beat until soft peaks form. Add the sugar gradually and beat until peaks are almost stiff.
  3. Add the beaten egg whites to the chocolate mixture in about four batches. Fold the egg whites into the mixture carefully with each addition. Here is a great video demonstrating folding.
  4. The mousse is ready when all the egg whites are incorporated and there are no lumps.

4 thoughts on “Chocolate Mousse Cake

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