Test Kitchen Tip: Wrap each individual blondie in waxed paper, then put them in a resealable bag for easy and cool transport. Test Kitchen Tip: Once you remove the coleslaw from the cooler, serve within two hours and discard any leftovers. Keep the dish out of the sun at the picnic site, so it doesn’t spoil. Test Kitchen Tip: Keep the dressing in a separate jar, and add it when you’re ready to eat the salad.