Ingredients:
- 1 ½ cups (190g) all-purpose flour
- ¾ cup (60g) unsweetened cocoa powder
- 1 ½ teaspoons baking powder
- 1 ½ teaspoons baking soda
- ¾ teaspoon salt
- 1 ½ cups (300g) granulated sugar
- ¾ cup (180ml) buttermilk, at room temperature
- ¾ cup (180ml) vegetable oil (canola or sunflower)
- 2 large eggs, at room temperature
- 2 teaspoons vanilla extract
- ¾ cup (180ml) boiling water
- 8 ounces (225g) good-quality bittersweet chocolate (60-70% cacao), chopped
- 1 cup (240ml) heavy cream, cold
- 2 large eggs, separated
- ¼ cup (50g) granulated sugar
- 4 ounces (115g) semi-sweet chocolate, chopped
- ½ cup (120ml) heavy cream
Instructions:
- Grease and flour two 8-inch round cake pans, line the bottoms with parchment paper.
- Whisk together flour, cocoa powder, baking powder, baking soda, and salt in a large bowl.
- In a separate bowl, whisk together sugar, buttermilk, oil, eggs, and vanilla extract.
- Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
- Slowly pour in the boiling water while mixing on low speed. The batter will be thin.
- Divide the batter evenly between the prepared cake pans and bake at 350°F (175°C) for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
- Let the cakes cool in the pans for 10 minutes, then invert them onto a wire rack to cool completely.
- Melt the chocolate in a double boiler or heatproof bowl set over simmering water, stirring until smooth. Remove from heat and let cool slightly.
- In a chilled bowl, beat the heavy cream with a mixer until stiff peaks form.
- In a separate bowl, beat the egg yolks and sugar until pale and thick.
- In a clean, dry bowl, whisk the egg whites until stiff peaks form.
- Gently fold the melted chocolate into the yolk mixture, then fold in the whipped cream, followed by the egg whites. Be careful not to deflate the mixture.
- Place one cake layer on a serving plate. Spread the chocolate mousse evenly over the cake layer. Top with the second cake layer.
- Refrigerate the cake for at least 1 hour to allow the mousse to set.
- Heat the heavy cream in a saucepan until simmering. Pour the hot cream over the chopped chocolate and let it sit for 1 minute. Whisk until smooth.
- Pour the ganache over the cake, allowing it to drip down the sides.
- Refrigerate for another 30 minutes to allow the ganache to set.
- Slice and serve cold.