This will depend on what ingredients you are putting in your casserole exactly. Whilst most casseroles can be frozen, certain ingredients used in them will preserve better when frozen either before or after they are cooked.u003cbr/u003eu003cbr/u003eGenerally speaking, perishable foods, such as eggs, should be frozen after they are cooked, whereas other dishes, such as those that use things like fish, should be frozen before they are cooked.u003cbr/u003eu003cbr/u003eMost vegetables do not take to freezing easily, so you should avoid freezing those casserole recipes that are primarily vegetable based.