Can you make a hash brown casserole ahead of time?
Yes, just cover the unbaked casserole and store it in the refrigerator for up to 3 days, then bake as directed. To freeze, tightly cover the unbaked casserole, and store it in an airtight, freezer-safe container in the freezer for up to 3 months. To serve, thaw in the refrigerator overnight and bake as directed.
— Alicia Rooker, RDN, Taste of Home Senior Recipe Editor/Recipe Tester