It's a rich gateau au chocolate like a ganache without flour. Good for Valentine's Day. Make a hard meringue.
I baked this cake for my chocoholic friend's birthday.
The tip is to whisk the heavy cream lightly. If you want to avoid the cake shrinking after baking, cover the cake with a dried kitchen towel just after baking and let it cool. It's better this way.
Enjoy Japanese food around the world.