Originally, the full title of this recipe was ‘Chestnut and porcini soup with porcini dust’, but the latter sounded way too cheffy and stuffy. That said, I’ve struggled to come up with a better way to describe the ground dried porcini powder that is sprinkled on top of the soup before serving. This final flourish lends an intense, almost woody flavour that lifts the soup into something quite special. Likewise, porcini stock cubes are worth seeking out and can be found in some large supermarkets, Italian food stores or online. A single cube adds a deep, rich base to this soup – autumn in a bowl.