With a few exceptions, casseroles lend themselves well to freezing. So what works and what doesn't? Dishes made with canned soups are great, freezer-ready meals that reheat so well many people swear they're better the second time around. However, dishes made with milk sauces don't work on ice because milk tends to separate or curdle when frozen. Also, potato-rich meals like hash brown casserole aren't ideal because, as we mentioned earlier, potatoes don't freeze well.
Whatever kind of casserole you decide to freeze, it'll keep for three to four months. Divide it into individual portions before freezing so you can reheat it in appropriately sized servings, and the smaller pieces will thaw more quickly.