Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan with gluten-free flour or cocoa powder, or line the bottom with parchment paper. For a cleaner release, you can also spray the sides with cooking spray.
1.5 cups unsweetened cocoa powder, dusting of cocoa powder
In a large bowl, whisk together the 1 ½ cups unsweetened cocoa powder, granulated sugar, light brown sugar, baking soda, and salt. Ensure there are no clumps, especially in the cocoa powder.
1.5 cups unsweetened cocoa powder, 1 cup granulated sugar, 0.5 cup packed light brown sugar, 1 teaspoon baking soda, 0.5 teaspoon salt
In a separate medium bowl, whisk together the almond milk, vegetable oil, and vanilla extract. Add the two large eggs one at a time, whisking well after each addition until fully incorporated.
0.75 cup unsweetened almond milk, 0.5 cup vegetable oil, 1 teaspoon vanilla extract, 2 large eggs
Pour the wet ingredients into the bowl with the dry ingredients. Mix with a whisk or electric mixer on low speed until just combined. Be careful not to overmix at this stage.
1.5 cups unsweetened cocoa powder, 1 cup granulated sugar, 0.5 cup packed light brown sugar, 1 teaspoon baking soda, 0.5 teaspoon salt, 0.75 cup unsweetened almond milk, 0.5 cup vegetable oil, 1 teaspoon vanilla extract, 2 large eggs
Gradually pour in the hot water or hot brewed coffee while mixing on low speed. The batter will be thin – this is normal and helps create a moist cake. Continue mixing until the batter is smooth.
0.5 cup hot water
Pour the batter into the prepared cake pan. Bake for 30-35 minutes, or until a wooden skewer inserted into the center of the cake comes out with moist crumbs attached (not wet batter).
Let the cake cool in the pan for about 15-20 minutes before inverting it onto a wire rack to cool completely. Ensure the cake is entirely cool before proceeding to the mousse layer.
Place the finely chopped bittersweet chocolate in a heatproof bowl. You can melt it using a double boiler (place the bowl over a saucepan of simmering water, ensuring the bottom of the bowl doesn't touch the water) or carefully in the microwave in 30-second intervals, stirring between each interval, until smooth and fully melted. Set aside to cool slightly.
1 pound bittersweet chocolate
In a separate large, clean bowl, whip the heavy cream (or full-fat coconut cream) with an electric mixer until soft peaks form. If using powdered sugar, gradually add it to the cream as you whip, continuing until stiff peaks form. Be careful not to over-whip, or it will turn into butter.
1.5 cups heavy cream, 2 tablespoons powdered sugar
Once the melted chocolate has cooled slightly (it should still be pourable but not hot), gently fold about a third of the whipped cream into the melted chocolate. This helps to lighten the chocolate and make it easier to incorporate the remaining cream.
1 pound bittersweet chocolate, 1.5 cups heavy cream
Gently fold the tempered chocolate mixture into the remaining whipped cream until no streaks of chocolate remain. Be very careful not to deflate the airy whipped cream. The goal is a light, fluffy, yet rich mousse.
1 pound bittersweet chocolate, 1.5 cups heavy cream
Once the cake base is completely cool, place it back into the cake pan (you can line the bottom with plastic wrap if you plan to unmold it easily, or just use the pan as is). Pour the chocolate mousse evenly over the cooled cake base. Use an offset spatula to smooth the top.
1 pound bittersweet chocolate, 1.5 cups heavy cream, 2 tablespoons powdered sugar
Cover the cake pan tightly with plastic wrap. Refrigerate for at least 4 hours, or preferably overnight, to allow the mousse to set completely.
Before serving, you can dust the top with cocoa powder, arrange fresh berries, or add chocolate shavings. Carefully remove the cake from the pan (if desired, especially if you lined it). Slice and serve chilled.
fresh berries, chocolate shavings, dusting of cocoa powder
