Cream of tartar is typically added to snickerdoodle recipes to give the cookies their signature fluffiness. Some claim that it adds a tangy flavor, but in my opinion, it does not, nor would I want a tangy flavor in my snickerdoodles Baking powder is the perfect substitute, as it contains an acid similar to cream of tartar, and is a more common leavener in bakers' kitchens! Baking powder gives these snickerdoodles the same fluffiness factor, and you don't have to make a trip to the store for a special ingredient!