Preheat the oven to 425 degrees.
Using a serrated knife, cut a long slit in the chestnut on the rounded side of the nut. Make sure you cut through the tough outer shell completely.
Put the chestnuts in a pot of water and bring to a boil.
When the water comes to a boil, remove the chestnuts with a slotted spoon and transfer to a baking sheet. Lay them flat side down in a single layer and roast them for 15 minutes. The shells split open as they cook.
Remove the chestnuts from the oven and transfer them to a bowl and cover them with a clean kitchen towel for about 15 minutes. This creates steam that will help the chestnut pull away from the shell.
Peel the chestnuts and enjoy!