1. Prepare the Chocolate Cake:

• Preheat your oven to 350°F (175°C). Grease and line the bottom of a 9-inch (23cm) springform pan with parchment paper.
• In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
• Add the eggs, milk, oil, and vanilla extract to the dry ingredients. Mix until well combined.
• Carefully stir in the boiling water until the batter is smooth (it will be thin).
• Pour the batter into the prepared pan and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
• Allow the cake to cool in the pan for 10 minutes, then remove from the pan and transfer to a wire rack to cool completely.

2. Prepare the Raspberry Mousse:

• In a small bowl, combine the lemon juice and gelatin. Let it sit for a few minutes to bloom.
• In a blender or food processor, puree the raspberries until smooth. Strain the puree through a fine-mesh sieve to remove seeds.
• In a small saucepan over medium heat, combine the raspberry puree and sugar. Stir until the sugar dissolves and the mixture is warm.
• Add the bloomed gelatin to the warm raspberry mixture, stirring until fully dissolved. Remove from heat and let it cool to room temperature.
• In a large mixing bowl, whip the cold heavy cream to stiff peaks. Gently fold the cooled raspberry mixture into the whipped cream until fully incorporated.

3. Assemble the Cake:

• Once the chocolate cake has cooled, place it back into the cleaned springform pan.
• Pour the raspberry mousse over the chocolate cake layer, smoothing the top with a spatula.
• Cover and refrigerate the cake for at least 3 hours, or until the mousse is set.

4. Prepare the Chocolate Ganache:

• In a small saucepan, heat the heavy cream over medium heat until it begins to simmer.
• Place the chopped chocolate in a heatproof bowl. Pour the hot cream over the chocolate and let it sit for a minute.
• Stir until the mixture is smooth and glossy. Allow the ganache to cool slightly until it thickens to a pourable consistency.

5. Finish the Cake:

• Remove the cake from the refrigerator and release it from the springform pan.
• Pour the cooled ganache over the top of the mousse layer, allowing it to drip down the sides.
• Garnish with fresh raspberries and chocolate shavings if desired.
• Refrigerate the cake for about 30 minutes to set the ganache before serving.