1. Preheat your oven to 350°F (175°C). Grease and line an 8-inch springform pan with parchment paper. This little prep trick helped me avoid the heartache of a cake stuck to the pan after the hundredth time I tried baking.
2. In a medium bowl, sift together the flour, cocoa powder, baking powder, and salt. Set aside.
3. In a large mixing bowl, whisk the egg yolks with half the sugar (1/4 cup) until pale and thick, about 3 minutes. This reminds me of standing on that wobbly chair next to my dad—watching the transformation of ingredients right before my eyes.
4. In a separate bowl, beat the egg whites until soft peaks form. Gradually add the remaining sugar and continue beating until you get stiff, glossy peaks.
5. Fold the egg whites gently into the egg yolk mixture, then fold in the dry ingredients until just combined. The key here is gentle folding to keep the batter light.
6. Pour the batter into the prepared pan and bake for 20-25 minutes, or until a toothpick inserted comes out clean. Let it cool completely on a wire rack.
7. While the cake cools, prepare the mousses. Melt each type of chocolate separately in a heatproof bowl over simmering water or in short bursts in the microwave, stirring until smooth.
8. Whip 1 cup of heavy cream until soft peaks form. Divide the whipped cream into three bowls.
9. Fold the dark chocolate into one bowl of whipped cream, the milk chocolate into the second, and the white chocolate into the third. Each mixture should be smooth and airy.
10. Slice the cooled cake horizontally into three even layers. Place the first layer on your serving plate or springform pan base.
11. Spread the dark chocolate mousse evenly over the bottom layer, then layer the second cake piece on top.
12. Spread the milk chocolate mousse over the middle layer, then add the top cake layer.
13. Finally, spread the white chocolate mousse over the top layer. Refrigerate the cake for at least 4 hours, preferably overnight, to let the mousse set beautifully.

One of my favorite things about this cake is how each mousse layer holds its own flavor, but when they come together, it’s like a little chocolate symphony. Patience is key here, and while the waiting is tough—I’ve learned to sneak tastes of mousse while stirring. Nothing wrong with a little quality control, right?