Yes, all casserole dishes are safe for the freezer. That being said, some types of casserole dishes (especially glass ones) will crack or even shatter if you move them suddenly from the oven or stove to the freezer. Check if your casserole dish is susceptible to this phenomenon, called “thermal shock.” If it is, make sure you allow your casserole dish to cool at room temperature before putting it in the freezer. Note that some casseroles may not taste so good after being frozen. For example, cooked cheese does not freeze too well.