Place the chestnuts flat side down on a cutting board. Using a sharp or serrated knife, score the chestnuts, making sure to go all the way through the shell.
Pre-heat the oven to 425ºF.
Place the scored chestnuts on a baking sheet with the scored side up. Roast in the oven for 20 minutes, or until the shells have peeled away from the nut inside. Remove the nuts from the air fryer and let them cool enough to be able to handle them.
Peel the shells off the chestnuts and discard. Use a paring knife to peel away the light brown skin to reveal the yellow nut.
Use the chestnuts whole in savory braised chicken dishes, chop them up to use in stuffings and dressings, or puree to use in sweet baking recipes or to make a chestnut cream.