Prepare the Chocolate Cake Layers:

• Preheat Oven: Preheat oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.
• Mix Dry Ingredients: In a large bowl, sift together flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt.
• Mix Wet Ingredients: In a separate bowl, mix buttermilk, vegetable oil, eggs, and vanilla extract. Gradually add the wet ingredients to the dry ingredients, mixing until smooth. Stir in boiling water until well combined.
• Bake: Divide the batter evenly between the prepared pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Cool in the pans for 10 minutes before transferring to a wire rack to cool completely.

2. Prepare the Raspberry Mousse:

• Blend Raspberries: In a blender, puree fresh raspberries, granulated sugar, and lemon juice until smooth. Strain the puree through a fine sieve to remove seeds.
• Dissolve Gelatin: In a small bowl, dissolve gelatin in water and let it bloom for 5 minutes. Heat gently until dissolved, then stir into the raspberry puree.
• Whip Cream: Whip heavy cream until soft peaks form. Gently fold the whipped cream into the raspberry mixture, then stir in vanilla extract.
• Chill Mousse: Chill the mousse in the refrigerator until it begins to set, about 1 hour.

3. Prepare the Chocolate Ganache:

• Heat Cream: Heat heavy cream in a small saucepan until just simmering. Remove from heat and add chocolate chips. Stir until smooth and glossy. Allow to cool slightly before using.

4. Assemble the Cake:

• Level Cake Layers: Once the cakes and mousse are completely cool, level the cake layers if necessary.
• Layer and Frost: Place one cake layer on a serving platter. Spread a layer of raspberry mousse over the cake, then top with the second cake layer. Frost the entire cake with chocolate ganache.
• Decorate: Decorate with fresh raspberries, mint leaves, and chocolate shavings if desired. Chill until ready to serve.