Throughout the northern Mediterranean littoral, chestnuts not only grow on trees; they fall to the ground each autumn and are, for many people, a free crop. (They once did the same on this continent, but blight wiped them out.)
The first fall I visited northern Italy, I saw them drop and realized there were more than anyone could possibly eat. As a result, they are used in a much wider array of dishes there than they are here. This is a rich soup, one that can be made in a matter of minutes with cooked, frozen, or even canned chestnuts, and the results are inevitably good. You can add flavor and substance to the soup by rendering a quarter cup or so of diced slab bacon, reserving the solids for a garnish and using some of the fat to sauté the celery and onion. A cup or so of shiitake mushroom caps, sliced and sauteed until crisp, makes a spectacular garnish if you happen to have some around. You can also add a little splash of port just before serving to give this a bit of a kick.