Dark Chocolate Mousse Cake

I've got a serious baking itch. It's a baking itch that cannot be scratched with Martha Stewart cupcake recipes or fun little ideas like cake pops or candy-filled brownies (understand, if you offer me one of these treats at any time I will still be powerless to turn them down). This is a really serious baking itch that needs to be scratched with french technique and complex multi-component desserts.

To segway into how I found this little cake recipe in front of you, I've got to start off by saying that the library is a wonderful place. After scouring Barnes and Noble, like I have on so many occasions, looking for the most advanced and complete baking book I could find I determined that if I wanted to purchase such a book I would have to wait until Christmas. And although Santa is generous, I just couldn't wait that long (the book I found weighed about 20 pounds and cost over $100). Hence, I turned to my trusty library to help me fill in the months until the holidays. It's not the first time either. I've previously taken out, and ravaged, the Martha Stewart Cupcake book. After making so many different cupcakes, cakes, and buttercreams I know for certain that I'm ready to learn more technique, and I can't wait to share with you all! Seriously, I'm way too excited for this :)

The book that I serindipitously picked out in less than a minute with my untuned-to-depth-perception two year old is EXACTLY what I need right now. It's a great beginners book to cakes. I feel like an over-ready beginner because even though I've made a hundred cake and frostings I've never actually learned anything but the basic butter-flour-sugar-baking soda cakes that we, as Americans, have grown so fond of. They are rampant on the internet and in popular media, but I've been craving something a little different and a little more unique. This first recipe definitly fit the bill! It is complex yet simple meaning that the components themselves are not overly skilled but that there are more than your average cake and they require some more time.

I made this dark chocolate mousse cake for my sister's 28th birthday. It is dark, chocolatey, moist, rich, and light at the same time. But the greatest part is that it's not too sweet. The layers of mousse are just as thick as the layers of moist delicate cake and the dark chocolate ganache is just the right "frosting" for this type of cake. If you love dark chocolate this is the cake for you!

Dark Chocolate Mousse Cake

For the sour cream cake layers:

1 3/4 cups all purpose flour

1 2/3 cups sugar

1/3 cup natural cocoa powder (not dutch processed)

1 tsp baking soda

2 large eggs

1/2 cup sour cream

2 tsp pure vanilla extract

1 stick (8 tbl) salted butter, melted and cooled

1/3 cup corn or vegetable oil

3/4 cup ice-cold water

Position a rack in the center of the oven and preheat the oven to 350 degrees. Grease the bottom and sides of a 9x3" springform pan. Line the bottom of the pan with a round of parchment paper, and grease the paper. Dust the paper and the sides of the pan with flour and tap out the excess.

Sift together the flour, sugar, cocoa powder, and baking soda into a medium bowl. Whisk to combine and set aside.

In another medium bowl, whisk together the eggs until blended. Whisk in the sour cream and vanilla extract until blended. Set aside.

In the bowl of an electric mixer fitted with the paddle attachment mix the melted butter and oil together at low speed. Add the cold water and mix to blend. Add the dry ingredients all at once and mix at medium-low speed for 1 minute. Add the egg mixture and mix for another minute, scraping down the sides of the bowl with a rubber spatula as necessary. Scrape the batter into the prepared pan.

Bake the cake for 45-50 minutes or until a toothpick inserted into the center comes out clean. Set the pan on a wire rack and cool the cake for 20 minutes. Invert the cake onto the rack, reinvert the cake, and cool completely. Make the chocolate mousse.

For the dark chocolate mousse filling:

9 ounces dark chocolate (at least 60%), coarsely chopped

1/2 cup whole milk

1/4 cup granulated sugar

1 tsp instant espresso powder

pinch salt

2 tsp vanilla extract

1 cup heavy cream

Place the chocolate in a large heat proof bowl and set aside.

In a small saucepan, combine the milk, sugar, espresso powder, and salt and bring to a boil over medium heat, stirring until the sugar dissolves. Pour the mixture over the chocolate, cover, and let sit 5 minutes. Uncover and stir until combined. Add in the vanilla and stir to combine. Let cool 10 minutes.

In the bowl of an electric mixer fitted with the whisk attachment beat the heavy cream until soft peaks form. Using a rubber spatula, gently fold 1/3 of the whipped cream into the chocolate mixture. Fold in the remaining cream until completely blended (the mousse should be used immediately).

To assemble the cake:

cooled sour cream chocolate cake

dark chocolate mousse filling

dark chocolate glaze (recipe below)

Using a long serrated knife, trim off the domed top of the cake so that the cake is perfectly level; reserve the trimmings. Cut the cake horizontally into 3 layers.

Place one of the cake layers in the bottom of a 9x3" springform pan. Scrape half of the chocolate mousse over the cake layer and spread it into an even layer. Top with another cake layer. Scrape over the remaining mousse and spread it into an even layer. Top with the remaining cake layer. Cover the top of the pan with plastic wrap or foil and freeze the cake for at least 3 hours, until firm.

Place the reserved cake trimmings in the bowl of a food processor and process to fine crumbs. Set aside. Make the dark chocolate glaze, if you have not already completed this step.

Remove the cake from the freezer. Run a sharp thin-bladed knife under hot water and wipe it dry. Run the kinfe between the cake and the side of the pan to release the cake; reheat the knife as necessary. Remove the side of the pan. Using a small offset spatula, smooth the mousse on the sides of the cake.

Place the cake on a wire rack and set the rack over a baking sheet. Pour the warm glaze over the top of the cake and use the offset spatula to smooth it evenly over the top and sides. Pat the cake crumbs over the sides of the cake. Refrigerate the cake for at least one hour (to thaw) before serving.

For the dark chocolate glaze:

6 ounces dark chocolate (at least 60%), coarsely chopped

2/3 cup heavy cream

1 tsp vanilla extract

In a small saucepan, bring the cream to a boil. Remove from the heat and add the chocolate. Stir until melted and combined. Add in the vanilla extract and stir to combine. Cover and let cool for 10 minutes before using.

Recipe adapted from The Cake Book by Tish Boyle.