Tuesday, December 22, 2020. December 22 is National Cookie Exchange Day. It is a day when cookies and tins appear at cookie parties. The host throws a holiday party for family and friends, to which everyone brings delicious homemade cookies to share around. Cookie exchanges are a centuries-old tradition dating back to medieval times. The classic idea is of a holiday party in which guests bring a selection of homemade cookies to trade with one another. Celebrate with a variety of cookies.