Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan. You can line it with parchment paper too if you want to avoid any cake mishaps later.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Add in the melted butter, eggs, milk, and vanilla. Mix until smooth.

Pour the batter into the prepared cake pan and bake for 25-30 minutes or until a toothpick comes out clean. Let it cool completely in the pan.

While our cake is cooling, melt the semi-sweet chocolate over a double boiler or in short bursts in the microwave. Once melted, set aside to cool slightly.

In another bowl, beat the egg whites with a pinch of salt until soft peaks form. Gradually add sugar until you reach stiff peaks. Set aside.

In a bowl, whip 1 cup of heavy cream until it forms soft peaks. In a different bowl, beat the egg yolks and mix them with the cooled chocolate and vanilla. Gently fold in the whipped cream followed by the egg whites.

Once the cake has completely cooled, slice it in half horizontally. Place the first layer on a serving plate, then layer half of the mousse mixture on top.

Gently place the second layer of cake, topping it with the remaining mousse. Cover and refrigerate for at least 4 hours (or overnight, if you can resist!).

To make the ganache, heat the heavy cream in a small saucepan until simmering. Pour it over the chopped dark chocolate and let it sit for 5 minutes. Stir until smooth.

Once your cake has chilled, pour the ganache over the top, allowing it to drip down the sides.

Slice and serve this rich masterpiece.