Prepare the Cake Layer

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease and line the bottom of a 9-inch round cake pan.
2. Mix the Dry Ingredients: In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
3. Cream the Butter and Sugar: In a separate large bowl, beat the softened butter and granulated sugar together until light and fluffy.
4. Add Eggs and Vanilla: Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
5. Combine the Wet and Dry Ingredients: Gradually add the dry ingredients into the wet ingredients, alternating with the milk, until the batter is smooth.
6. Bake: Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.

Prepare the Raspberry Mousse

1. Prepare the Gelatin: In a small bowl, sprinkle the gelatin over 2 tablespoons of water. Let it bloom for 5 minutes, then microwave for 10-15 seconds to dissolve.
2. Whip the Cream: In a large mixing bowl, whip the heavy cream until stiff peaks form. Set aside.
3. Blend the Cream Cheese and Sugar: In another bowl, beat the softened cream cheese and powdered sugar together until smooth.
4. Add Raspberry Puree: Mix in the raspberry puree and vanilla extract until combined.
5. Fold in Whipped Cream: Gently fold the whipped cream into the raspberry mixture, making sure it stays light and airy.
6. Add Gelatin: Stir the dissolved gelatin into the mousse mixture, combining thoroughly.
7. Chill: Spread the raspberry mousse evenly over the cooled cake layer. Refrigerate for at least 2 hours, or until the mousse has fully set.

Prepare the Chocolate Ganache

1. Heat the Cream: In a small saucepan, bring the heavy cream to a simmer over medium heat.
2. Add Chocolate: Remove the cream from heat and pour it over the chocolate chips. Stir until smooth and glossy.
3. Finish with Butter: Add the softened butter to the ganache and stir until fully incorporated.
4. Pour Ganache over Cake: Once the mousse has set, pour the ganache over the top, smoothing it out with a spatula to cover the entire cake.