Chocolate cake

1. Preheat the oven to 170°C (338°F).
2. Warm the milk until it’s very hot.
3. In a mixing bowl, add the cocoa powder, then pour the hot milk on top and mix until it forms a smooth paste.
4. Add the oil, egg, sugar, all-purpose flour, baking powder, and baking soda. Mix until well combined.
5. The batter will be smooth and ready to bake. Pour it into a lined baking pan and bake for 25 to 30 minutes.
6. Check if the cake is fully cooked by inserting a wooden toothpick into the center—it should come out clean or with a few moist crumbs.
7. Let the cake cool completely. Then, carefully cut off the top crust to create a soft, even cake base.
8. Remove the parchment paper gently, as this cake tends to crumble.
9. Place the cake back into the pan and line the sides with a clear acetate collar to prepare for the mousse layer.

Chocolate mousse 

1. In a pan, combine most of the sugar (reserve about 2 tablespoons for whipping the cream) and milk. Bring to a boil.
2. In a separate bowl, whisk the egg yolks. Slowly pour the hot milk mixture into the yolks while whisking continuously to temper the eggs.
3. Pour the mixture back into the pan and cook on low heat for about 3 minutes, stirring constantly.
4. Place chopped dark chocolate in a bowl and pour the hot mixture over it through a sieve to ensure a smooth texture. Mix until the chocolate is fully melted.
5. Hydrate 2 gelatin sheets in cold water 2 to 3 minutes, then add them to the chocolate mixture. Stir until fully dissolved.
6. Whip the heavy cream with the reserved sugar until soft peaks form. Use a whisk or electric mixer.
7. Gently fold the whipped cream into the chocolate mixture, being careful not to overmix.
8. Pour the mousse on top of the chocolate cake, tap the pan to remove air bubbles, and refrigerate for at least 6 hours to set.

Chocolate ganache

1. Place chopped dark chocolate in a heat-resistant bowl.
2. To make the dark chocolate ganache, start by warming up the heavy whipping cream in a pan. Once it begins to slightly boil, pour it over the chocolate and mix gently until the chocolate is completely melted. Avoid stirring too much, as this can create extra bubbles in the ganache.
3. If the chocolate hasn’t fully melted, use the bain-marie (double boiler) method to finish melting it. Be careful not to overheat the chocolate, as it can split.
4. Allow the ganache to cool slightly before pouring it over the mousse cake. If the ganache is too hot, it will melt the mousse layer.
5. Now, you’ll have a beautiful dark chocolate mousse cake with ganache that’s ready to serve and enjoy!