Pumpkin-Chestnut Soup

No-hull seeds from pumpkins such as 'lady godiva, Roasted dried

Onions, medium

Waxy potatoes, large

Chicken or vegetable stock, homemade or low-sodium store-bought

Salt and freshly ground pepper, Coarse

jar Chestnuts, whole

Butter, unsalted

Heavy cream

4 pounds roasted flesh of dry, starchy pumpkin or squash, such as 'Hubbard' or 'Buttercup,' cut into 1-inch cubes