HOW TO MAKE A CHOCOLATE MOUSSE CAKE RECIPES

Steps:

• Make the cake: Preheat the oven to 350˚ F. Butter a metal 8-inch square cake pan. Line the bottom and sides of the pan with parchment paper; lightly butter the parchment. Combine the cocoa and espresso powders in a medium bowl. Heat the milk and butter in a small saucepan over medium-low heat until the milk is steaming and the butter melts. Whisk into the cocoa mixture; let cool to room temperature.
• Whisk the flour, baking powder, baking soda and salt in a medium bowl. In a large bowl, beat the eggs and sugar with a mixer on medium-high speed until very pale, thick and pillowy, 5 to 8 minutes. Beat 30 to 45 more seconds to stabilize the egg foam.
• Reduce the mixer speed to low; beat in the cocoa mixture in 2 additions, alternating with the flour mixture in 2 additions. Beat just until the batter is smooth and no dry flour remains.
• Pour the batter into the cake pan and gently tap against the counter to eliminate any air bubbles. Bake until a toothpick inserted into the center comes out clean, about 35 minutes. Let cool 10 minutes in the pan, then turn out the cake onto a rack. Peel off the parchment but let it rest gently on top of the cake while it cools completely. Wipe the cake pan clean and reserve.
• Make the ganache: Combine 1/2 cup heavy cream, 4 ounces chocolate and 1 tablespoon butter in a small saucepan. Gently cook over medium-low heat, stirring, until melted and smooth. Let cool.
• Make the mousse: Combine the remaining 4 tablespoons butter and 4 ounces chocolate in a small microwave-safe bowl. Microwave in 30-second intervals, stirring, until melted and smooth. Whisk in the cocoa powder until smooth. Let cool.
• Meanwhile, combine 1/4 cup heavy cream and the gelatin powder in a small microwave- safe bowl. Let stand until the gelatin absorbs the liquid, about 5 minutes, then microwave until melted, 20 to 30 seconds, whisking. Let cool, stirring occasionally.
• Combine the remaining 1 1/4 cups heavy cream, the sugar and espresso powder in a large bowl. Beat with a mixer on medium speed to dissolve the sugar, about 1 minute. Stream in the cooled gelatin mixture, then increase the speed to medium high and beat until the mixture is thick and stiff peaks form. Fold in the cooled chocolate mixture in 2 or 3 batches until the mousse is well blended.
• Assemble the cake: Line the reserved cake pan with 2 crisscrossed strips of parchment paper (this will help you lift out the finished cake). Carefully slice the cake horizontally into 3 equal layers. Lay the best layer cut-side up in the bottom of the pan and brush with some of the chocolate liqueur, if using. (Use a plate or small cutting board to move the layers; if your top cake layer is domed, use it for the middle of the cake.) Evenly spread half of the mousse on top with an offset spatula, all the way to the edges. Top with a second cake layer. Brush again with chocolate liqueur, then spread half of the ganache evenly on top. Add the final cake layer, cut-side up, and brush with the remaining liqueur. Top with the remaining mousse and ganache. (The assembled cake should fill the pan.)
• Refrigerate the cake until the top is set, about 30 minutes, then wrap the whole cake pan with plastic wrap and refrigerate overnight to set completely. 
• Lift the cake out of the pan using the parchment pieces and transfer to a cutting board. Using a hot, dry serrated knife, slice the cake, wiping the knife in between cuts for clean edges.

Steps:

• Make the cake: Adjust racks to center and lower-third position, and preheat oven to 350°. Line 3, 8” cake pans with parchment, and grease with cooking spray. Place chocolate in a heat-safe bowl and set over a pan of simmering water, ensuring bottom of bowl doesn’t touch water. Stir until chocolate is completely melted and smooth. Remove from heat and let cool to room temperature. 
• In a large bowl, whisk together flour, baking powder, and salt. 
• In another large bowl using a hand mixer, or in the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition, then add vanilla. Add half of the dry ingredients and beat until just a few dry streaks remain. Add milk and sour cream, and beat until incorporated. Add remaining dry ingredients and beat until just combined. Divide batter evenly between cake pans, and smooth tops with an offset spatula. 
• Bake until a toothpick inserted in middle comes out clean, 28 to 30 minutes. Let cool 10 minutes, then invert onto a cooling rack and let cool completely. 
• Make the mousse: Place chocolate in a small heat-safe bowl. In a small pot over medium heat, heat ¼ cup cream until simmering. Pour over chocolate and let sit for 1 minute, then stir until smooth. Refrigerate to let cool completely, about 10 minutes. Give the mousse a stir after about 5 minutes to make sure the chocolate isn’t hardening. 
• Meanwhile, place remaining ¾ cup heavy cream in bowl of a stand mixer fitted with the whisk attachment, and beat until stiff peaks form. Gently fold in cooled chocolate mixture until just combined. 
• Make the frosting: In a large bowl using a hand mixer, or in bowl of a stand mixer fitted with the paddle attachment, beat cream cheese and butter until smooth. Add powdered sugar and beat until no lumps remain, then add in vanilla. 
• Make ganache: Place chocolate in a small heat-safe bowl. In a small pot over medium heat, heat ¼ cup cream until simmering. Pour over chocolate and let sit for 1 minute, then stir until smooth.
• Assemble cake: Using a large serrated knife, level tops of cakes as needed. Place one layer on a serving dish, and top with half of the mousse. Smooth into an even layer. Top with a second layer of cake, then remaining mousse. Top with third layer of cake. 
• Frost top and sides with cream cheese frosting, reserving some to pipe onto top of cake, if desired. Spoon ganache over top of cake, and let drip down the side. 
• If desired, place reserved frosting into a pastry bag with a large open star tip, and pipe dollops around edge of cake. Sprinkle top with chocolate shavings.