You can freeze it! If fully baked, allow it to cool all the way before freezing in a freezer safe container. If you are baking it as a whole casserole, you can leave it whole. Do not freeze it in glass due to the safety concerns of extreme temperature changes. You can also freeze it in individual portions to reheat as needed. It should last 3-4 months if frozen properly. You can freeze it before baking as well. Just be sure that it is cooled completely before freezing.