Finely dice the pumpkin flesh. Sweat the onions and pumpkin in oil. Pour in the broth and bring to the boil. Season with salt, pepper, a little coriander and ginger. Simmer over low heat until the pumpkin flesh is tender.
Add the chestnuts and heat, save a few chestnuts for later. Puree the soup, bring to the boil again briefly. Fold in the creme fraîche, season again if necessary.
Cut the chestnuts set aside into small cubes. Toast in hot clarified butter. Arrange in preheated plates. Spread the roasted chestnuts on top and drizzle pumpkin seed oil over them.