This is a great cake — it is basically a cooked mousse, it puffs up high during cooking and collapses once removed from the oven to form a dense centre. It’s best eaten within 4 hours of baking, as the top remains crisp during this time, adding another delicious texture to the cake. The beauty of this cake, and any other chocolate products for that matter, is that short of burning them you will end up with an acceptable product even if something goes wrong.