Crinkle cookies, also called crackle cookies, are soft, fudgy cookies rolled in powdered sugar before baking, so the dough cracks as it spreads, leaving a crackled white-and-dark surface.
Chocolate is the classic version, popular in American holiday baking since at least the mid-20th century; other flavors include peanut butter, red velvet, and seasonal variants like peppermint or gingerbread.
The defining trait is a soft, fudgy interior under a cracked sugar crust, which sets crinkle cookies apart from crumbly, shortbread-style cookies.