Chocolate Mousse Cake

Ingredients

 Cake

• ¾ cup (143g) granulated sugar
• ¼ cup (59ml) vegetable oil
• 2 large eggs, at room temperature 
• 2 teaspoons (10ml) vanilla extract
• ¼ cup (48g) sour cream, at room temperature 
• 1 cup (140g) all-purpose flour, sifted
• ¼ cup (20g) cocoa powder, sifted (I use Hershey’s Special Dark)
• 1 ¼ teaspoons (4.6g) baking powder
• ¼ teaspoon baking soda
• ½ teaspoon salt
• 2/3 cup (157ml) hot brewed coffee

Chocolate Layer

• 1 tablespoon (15ml) cold water
• 1 teaspoon powdered gelatin
• 1 cup plus 2 tablespoons (266ml) heavy whipping cream, divided
• 4 ounces (113g) dark chocolate, roughly chopped 
• ½ cup (65g) powdered sugar
• 8 ounces (226g) cream cheese, at room temperature 
• ¼ cup (48g) granulated sugar
• 2 teaspoons (5g) cocoa powder
• 1 teaspoon (5ml) vanilla extract

Ganache

• 2 ounces (75g) dark chocolate, chopped
• 6 tablespoons (90ml) heavy whipping cream

Whipped Topping

• 1 cup (236ml) heavy whipping cream, cold
• ½ cup (65g) powdered sugar
• 2 tablespoons (10g) cocoa powder
• 1 teaspoon (5ml) vanilla extract

Method

Cake Layer

1. Preheat the oven to 350°F. Line an 8-inch cake pan with parchment paper or a silicone baking mat and grease & flour the edges.
2. In a large mixing bowl, combine the sugar, vegetable oil, eggs, and vanilla extract. Beat on medium speed until the eggs and oil are well incorporated and the batter is lighter in color. Next mix in the sour cream and beat until well combined.
3. In a separate bowl, sift together the dry ingredients. Add half the dry ingredients to the wet ingredients, followed by half of the coffee, and mix until the flour is just incorporated at a low speed. Then add the remaining dry ingredients and coffee. Beat until all of the ingredients are well combined. Use a spatula to scrape down the sides of the bowl and stir the batter from the bottom to the top to ensure it’s well mixed.
4. Bake at 350°F for 28-32 minutes. Test the cake for doneness by inserting a toothpick into the center of the cake. If the toothpick comes out clean, the cake is done. Cool Completely.

 Mousse Layer

1. Place the mixing bowl and whisk attachment in the freezer for 5 to 10 minutes to chill while you are preparing the next steps.
2. Place 1 tablespoon of cold water in a small dish. Sprinkle the gelatin over the cold water, trying to spread the powder evenly. Allow the gelatin to turn to a solid (about 2-3 minutes)
3. In a microwave-safe bowl, combine the chocolate and 2 tablespoons of heavy whipping cream. Microwave in 30-second increments, stirring each time until the chocolate is melted.
4. Next, melt the gelatin in the microwave for 5-8 seconds until it turns back into a liquid. Watch it closely! Remove any lumps that did not melt.  Stir the liquid gelatin into the melted chocolate and set it aside to cool.
5. Prepare the whipping cream. Using the chilled bowl, beat the heavy cream on high speed until it’s thickened to soft peaks. Next, add the powdered sugar and continue beating at high speed until stiff peaks form. Set the whipped cream aside.
6. Beat the cream cheese until it’s completely smooth and free of lumps. Scrape down the sides of the bowl, add the granulated sugar, cocoa powder, and vanilla extract, and beat until well combined.
7. Next add the melted chocolate, beating until it’s completely mixed into the cream cheese, scraping down the bowl as needed. Lastly, fold in the prepared whipped cream and mix until all ingredients are combined.

Assemble

1. Transfer the cake layer to an 8-inch springform pan, or line the cake pan with plastic wrap or parchment paper along the bottom and up the sides if you want to remove the cake from the pan. Place the cake in the bottom of the pan. Pour the chocolate filling over the chocolate cake, spread evenly, and refrigerate until the filling is set, 2-4 hours.

Chocolate Ganache

1. In a microwave-safe bowl, combine the chocolate and heavy whipping cream. Melt the chocolate in the microwave at 50% power in 30-second increments and stir until completely combined. Allow to cool.
2. Pour the chocolate over the mousse layer and spread evenly. Allow the ganache to set a little bit before adding the topping.

Topping

1. Prepare a second batch of whipped cream following the same instructions above, adding the cocoa powder together with the powdered sugar and vanilla. Pipe the border using a large open star tip.