Yes this fish pie is a great dish for batch cooking as it can be frozen for up to 3 months. Just place it in an airtight container and put it in the freezer once it has cooled. You can reheat from frozen or defrost first. Reheat in the oven for the best results, but you can also microwave it if you are in a rush. If you are making a fish pie with the intention of freezing it I recommend skipping the baking step and freezing the assembled fish pie once it has cooled. This way you will get a freshly cooked grilled cheese topping when you come to eat it.