Preheat oven to 400 degrees F.
If chestnuts are dirty, wipe with a damp cloth. Use kitchen shears to snip a small cut into each shell or cut an X into one side of each chestnut with a paring knife Ð this will keep them from exploding in the oven.
Roast on a cookie sheet for 15 to 25 minutes, or until chestnuts are tender Ð test by eating one. Let them cool a bit and serve warm.