Frozen casseroles are the perfect solution to a busy day. With a premade, frozen casserole, you just need to thaw and reheat the casserole to have a delicious meal. Unlike fruits, vegetables, meats and dairy products, previously cooked food doesn't have to be thawed, which saves you a step in reheating the casserole. Casseroles made from noodles can be heated quickly in a double boiler, but for the most part a casserole can be reheated in the oven. The casserole needs to reach an internal temperature165 degrees F within 2 hours.
Preheat the oven to 350 degrees F.
Place your casserole in the oven. If the frozen casserole is in a glass container, check that the manufacturer instructions say it is safe to put in the oven while cold. If not, or if you are unsure, carefully transfer the frozen casserole into an oven-safe baking dish.
Cook the casserole until it reaches an internal temperature of 165 degrees F. You can check the temperature with a meat thermometer. You will need the casserole to be in the oven for about twice the amount of time it originally took to cook.
Remove the casserole once it is hot and serve.