You can store blondies for up to 3 days at room temperature or up to a week in the fridge. If storing for more than a day, wait to slice blondies into bars until you’re ready to serve to prevent stale edges. You can also freeze up to 3 months in an airtight container. Thaw overnight at room temperature then refresh in a 325°F oven for about 5 to 10 minutes.