Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan.

In a mixing bowl, whisk together the flour, baking powder, baking soda, cocoa powder, and sugar until well combined.

Add the softened butter, eggs, vanilla extract, and milk. Mix until smooth and well incorporated.

Pour the batter into your greased cake pan and bake for about 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, let it cool for about 10 minutes, then flip it out onto a wire rack to cool completely.

Melt the chopped chocolate in a heatproof bowl over a simmering pot of water. Stir until smooth and let it cool slightly.

In another bowl, whip the heavy cream until soft peaks form. Gradually add the powdered sugar and vanilla extract, continuing to whip until you get stiff peaks.

Gently fold the melted chocolate into the whipped cream until fully combined.

Once the cake is completely cool, slice it in half horizontally to create two layers.

Place the bottom layer on a serving plate and spread half of the chocolate mousse on top.

Gently place the second cake layer on top and spread the remaining mousse over the top and sides of the cake.

Decorate with fresh raspberries and perhaps a sprinkle of mint leaves.