Preheat oven to 425 degrees and get out a large rimmed baking sheet.
Take a sharp pairing knife and slit a line through the nut's skin horizontally on the flat side of the nut. This will make it easy for the nut to crack open while roasting.
Roast the chestnuts for 20 minutes or until they start to pry open (some larger nuts take a bit longer to crack open). Crack open with your hands, discard skin, and enjoy the golden brown nut in the center.
Roasted chestnuts can be stored at room temp for a few days.
