Try this Creamy Chestnut Soup recipe.
Undercooking or improperly peeling the chestnuts ruins the texture of chestnut soup before simmering even begins. Scoring a deep 'X' into the flat side of each nut and roasting them at 200 degrees Celsius ensures the inner skin releases cleanly alongside the rigid outer shell. When dealing with variable yields or scaling quantities for larger groups, maintaining the ratio of starchy solids to liquid prevents the broth from turning thin or watery. Roasting also introduces a deeper caramelized flavor profile than raw blanching ever achieves. Boiling the shelled nuts with onion, celery, and a bay leaf for thirty minutes softens the dense starches completely.
Thickening requires combining flour and butter into a smooth paste rather than tossing them separately into the hot pot. Kneading equal parts softened fat and flour creates a traditional beurre manie that disperses evenly without forming stubborn lumps. Simmering this mixture for one minute activates the starch to bind the milk and cooking liquid together. Pressing the final mixture through a fine metal strainer or puree sieve removes any remaining fibrous particles from the celery or chestnut skins. For a dairy-free adaptation, substitute the whole milk with unsweetened almond milk and replace the butter with an equal weight of refined coconut oil.