Preheat the oven to 425 degrees.
Using a sharp paring knife, make an X-shaped cut on the round side of each chestnut.
Don't skip this step because it keeps them from exploding when heated.
Arrange the chestnuts in a cast iron skillet or baking dish.
Place the chestnuts in the oven and roast them until the skins have pulled back from the cuts and the nut inside has softened, about 20 minutes.
Remove the nuts from the oven, make a mound of them in an old towel, wrap them up, squeeze them hard.
Let them steam for a few minutes in the towel.
Peel the chestnuts and eat plain or saute them in some butter with a pinch of cinnamon and salt. Enjoy.