I referred to Recipe ID: 1029190 to make the cocoa sponge cake, which is just a basic tiramisu sponge. Cut the edges to fit the cake mold.
I referred to Recipe ID: 938597 to make the white chocolate mousse. Pour the mousse on top of Step 1 and chill in the refrigerator.
Make the chocolate mousse...Place the chocolate in a bowl and melt it on a double broiler. Leave it as is on the double broiler to keep warm.
Put the egg whites in a separate bowl. While adding the 15 g of sugar a little bit at a time, whip until soft peaks form. (Leave on standby in the refrigerator.)
In a separate bowl, add the heavy cream, rum, and 10 g of sugar. Whip until thickened. (Leave on standby in the refrigerator)
Heat the milk in a pot. When the edges begin to bubble, remove from heat and add the dissolved gelatin.
Slowly add the mixture from Step 6 into the chocolate from Step 3. Mix really well.
Here you strain Step 7, but if you mix it thoroughly and evenly enough, you don't need to.
Chill the bottom of the Step 8 bowl with cold water and when it thickens, Mix in the meringue from Step 4 and the heavy cream from Step 5 alternating between the two.
Pour Step 9 on top of the chilled Step 2 and chill in the refrigerator until it hardens. (I left it to harden in the refrigerator for one day)
Once it hardens, remove from the mold, dust with cocoa powder, and it's finished...
Story Behind this Recipe
Both the white chocolate mousse and the chocolate mousse recipes are delicious. So if the two are extravagantly put together, they must become even more delicious...and it was so, so, so good.
If you don't line the mold with parchment paper, it maybe comes out prettier? Adding a good amount of gelatin to the white chocolate mousse and chocolate mousse makes it properly firm. If you don't add the white chocolate to the white chocolate mousse mixture, it will just be a bavarois, which is also very tasty.