"To biscochar (crispen) the cookies, lower oven temperature to 200° F, put baking sheets in oven for one hour, turn oven off, allow cookies to remain in oven overnight." (Sephardic Heritage Cookbook: Ottoman, Persian, Moroccan, Egyptian Recipes and More by Sephardic Temple Or Chadash Sisterhood)
"Biscochar (crisp) the cookies by placing bracelets on a baking sheet and leave in the oven for one hour." (source)