Preheat oven to 425°F (220°C)
Make an X-shaped slit in the flat side of each chestnut using a sharp knife
Place chestnuts on a baking sheet in a single layer
Roast for 15–25 minutes, shaking or turning once halfway
Chestnuts are done when shells peel back and nuts are tender
Remove from oven and immediately wrap in a clean kitchen towel for 5–10 minutes
Peel while warm, checking for any that need a little more roasting
If roasting in batches, keep remaining chestnuts covered to prevent drying