A "cookie tin" refers to a metal or plastic container used for storing cookies. It is commonly used to keep cookies fresh and prevent them from getting stale. Full definition
We packed them up in cookie tins, cut out some gift tags, and the instructions, and drove over to her house to spread a little holiday cheer! (homemadeinterest.com)
I plan to get cute cookie tins at the dollar store. (slim-shoppin.com)
Leave clients with a satisfying taste for your business — all wrapped up in a customized cookie tin filled with holiday goodies. (realtormag.realtor.org)