Once cooked, leftovers can be kept for up to 3 days in the refrigerator. Store in an airtight container and reheat in the oven or microwave. You can also freeze Cracker Barrel hash brown casserole! It will keep for up to 3 months, whether cooked or uncooked. Simply thaw in the refrigerator overnight, then bake as directed or reheat for 20-25 minutes at 350°F.