Roast Duck with Chestnuts

In Sardinia ducks are always wild, never farmed, or at least they’re not farmed for meat – the only ducks we ever kept in the yard were used for eggs. You can prepare the duck and sauce for this dish a day ahead and then assemble it just before serving; if you do this, remove the duck from the fridge 30–60 minutes before reheating to bring it to room temperature. The chestnut purée recipe makes more than you’ll need, but the leftovers are great as a dip with bread, crackers or raw vegetable