Gâteau au Chocolat Lyonnaise

I think of this cake as chocolate mousse miraculously held together by potato starch, which yields a crisp crust and a soft and tender interior. The mixing method is quite strange, but I have always followed it to the letter and have had no trouble. The recipe comes from the back of a chocolate package I came across in Lyon, a city renowned for its chocolate fantasies. Gâteau au Chocolat Lyonnaise is served at room temperature and cuts like a sponge cake, though it tastes more like a luxuri