Toast the walnuts lightly. Line the bottom of the cake pan with parchment paper. Do not grease it with butter. The cake will not come off. Preheat the oven to 170℃.
Crush the cookies/biscuits and walnuts and mix them with the melted butter.
Put the chocolate and butter in a bowl and melt them together either by immersing them in a water bath or by microwaving them. Once they've melted, sift in the ingredients marked with ● and mix it all together with a whisk.
Add the granulated sugar little by little to the egg whites and whip them into a stiff meringue.
Add 1/3 of the meringue you made in step 4 to the chocolate (step 3) and stir it in with a round motion using a whisk. Once you do this, the batter will separate and look dry and crumbly, with an oil-like appearance on top.
Mix it well to emulsify it and create a glossy batter.
Once it has become a glossy batter, add the rest of the meringue. Swap your whisk for a spatula and fold in the meringue with it while taking care not to crush the air bubbles.
Pour the batter into the cake pan. Place the cake pan onto a sheet pan and submerge it in 2-3 cm of hot water. Bake the cake with the water for about 40 minutes.
Once the cake is finished baking, do not remove it from the pan straight away. Once the pan has cooled enough to touch, place it and the cake in the fridge, and once it has cooled completely, remove the cake from the pan and cut it.
Garnish the cake with as much cream or other topping as you like, and it's finished. This has a texture like rich ganache.
Story Behind this Recipe
I wanted to add a brittle texture to rich chocolate cake, so I made a base and created a very delicious final product.
Since you'll be baking this in a water bath, be sure to use a pan whose bottom doesn't come off. Please emulsify the meringue with the rest of the batter well once you've added it.