Triple Layer Chocolate Mousse Cake

**Ingredients:**

**For the Chocolate Cake Base:**

* 1/2 cup (60g) all-purpose flour
* 1/2 cup (100g) granulated sugar
* 1/4 cup (25g) unsweetened cocoa powder
* 1/2 teaspoon baking soda
* 1/4 teaspoon baking powder
* 1/4 teaspoon salt
* 1/4 cup (60ml) milk
* 2 tablespoons vegetable oil
* 1/2 teaspoon vanilla extract
* 1/4 cup (60ml) hot water

**For the Dark Chocolate Mousse Layer:**

* 6 ounces (170g) bittersweet or semi-sweet chocolate, chopped
* 1 cup (240ml) heavy cream, divided
* 1 teaspoon unflavored gelatin powder
* 2 tablespoons cold water

**For the White Chocolate Mousse Layers:**

* 12 ounces (340g) white chocolate, chopped
* 2 cups (480ml) heavy cream, divided
* 1 1/2 teaspoons unflavored gelatin powder
* 3 tablespoons cold water

**For the Whipped Cream Topping:**

* 1 cup (240ml) heavy cream
* 2 tablespoons powdered sugar
* 1/2 teaspoon vanilla extract

**For Garnish:**

* Chocolate shavings or curls

**Instructions:**

**1. Make the Chocolate Cake Base:**
* Preheat oven to 350°F (175°C). Grease and flour a 9-inch springform pan.
* In a medium bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.
* Add the milk, oil, and vanilla, and mix until just combined. Slowly pour in the hot water and stir until the batter is smooth. The batter will be thin.
* Pour the batter into the prepared pan and bake for 15-20 minutes, or until a toothpick inserted into the center comes out clean.
* Let the cake cool completely in the pan on a wire rack. Once cool, make sure the cake layer is flat. If it has domed, gently press down or trim the top to create a flat surface.

**2. Make the Mousse Layers (start with white chocolate):**
* **White Chocolate Mousse:** In a small bowl, sprinkle gelatin over 3 tablespoons of cold water and let it bloom for 5 minutes.
* In a microwave-safe bowl, heat 1/2 cup of the heavy cream until hot but not boiling. Add the bloomed gelatin and stir until completely dissolved.
* Add the chopped white chocolate to the hot cream and let it sit for 2 minutes, then whisk until smooth. Set aside to cool to room temperature.
* In a separate large bowl, whip the remaining 1 1/2 cups of cold heavy cream until soft peaks form.
* Gently fold half of the whipped cream into the cooled white chocolate mixture until combined. Then, fold in the remaining whipped cream. Divide the mousse mixture into two equal portions.

**3. Assemble the First Layers:**
* Place the cooled chocolate cake base in the springform pan.
* Pour one portion of the white chocolate mousse over the cake base. Gently smooth the top with a spatula.
* Refrigerate for at least 30-40 minutes to allow the mousse to set.

**4. Make the Dark Chocolate Mousse Layer:**
* While the first layer is chilling, prepare the chocolate mousse. In a small bowl, sprinkle gelatin over 2 tablespoons of cold water and let it bloom for 5 minutes.
* In a microwave-safe bowl, heat 1/4 cup of heavy cream until hot. Add the bloomed gelatin and stir until dissolved.
* Add the chopped bittersweet chocolate to the hot cream mixture and let it sit for 2 minutes, then whisk until smooth. Let it cool to room temperature.
* In a separate bowl, whip the remaining 3/4 cup of cold heavy cream to soft peaks.
* Gently fold the whipped cream into the cooled chocolate mixture until no streaks remain.

**5. Assemble the Middle and Top Layers:**
* Remove the chilled cake from the refrigerator.
* Pour the dark chocolate mousse over the set white chocolate layer and smooth the top.
* Refrigerate for another 30-40 minutes to set.
* Once the dark chocolate layer is set, carefully pour the second portion of white chocolate mousse on top and smooth it out.
* Refrigerate the cake for at least 4-6 hours, or preferably overnight, to allow all the layers to set completely.

**6. Prepare the Topping and Garnish:**
* When the cake is fully set, remove the springform ring.
* In a cold bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
* Pipe the whipped cream in decorative swirls around the top edge of the cake.
* Sprinkle the center and the whipped cream with generous amounts of chocolate shavings.
* Slice the cake with a hot, clean knife for a perfect presentation and serve immediately.