Learning how to reheat a casserole in the oven can be the difference between a mediocre leftover meal and a delicious dish that’s almost as good as when it first came out of the oven. Whether it’s a hearty ground beef casserole, an egg casserole, or a cheesy vegetable bake, the best way to warm up leftover casserole (or frozen and made-ahead casseroles) lies in understanding the best practices of the reheating process. You need to ensure your casserole is hot throughout, maintains its moisture, and retains the right textures. There are a few different ways to achieve the right temperature and cooking process. Let’s get baking!

how to reheat a casserole in the oven

What is a Casserole?

So, what actually constitutes a casserole, anyway? The casserole is a one-dish wonder that usually combines meat, vegetables, and starches, all brought together with a delicious sauce. Topped with cheese, breadcrumbs, or crispy onions, a casserole is designed to be baked and served hot, making it a staple for easy dinners and a favorite at potlucks. But the beauty of a casserole doesn’t end on the first day; many casseroles taste even better the next day, as the flavors meld together in the refrigerator overnight. To be honest, anything that you whip-up and slap in a baking dish is a casserole in my book!

Different Types of Casseroles

Casseroles come in many varieties, making them a versatile option for any meal. Breakfast casseroles might include eggs, sausage, and cheese, perfect for the next morning’s meal. Meat casseroles, like a ground beef casserole or a chicken bake, are hearty dinner options. For vegetarians, vegetable casseroles offer a delicious and healthful dish. No matter the type of casserole, the principles of reheating for great results remain the same.

noodle bake with ham
Leftover Ham & Noodle Casserole Recipe

Oven Temperatures and Cook Times

First of all, be sure any casserole that you’re reheating has been properly stored in an airtight container (or at least covered with plastic wrap.) This keeps contaminants out and ensures your casserole is ready to hit the oven. 

Warm-Up from Refrigerated

A refrigerated casserole should be brought to room temperature for even heating before it goes into the oven. Preheat your oven to a moderate temperature—350°F (175°C) is a general rule. Covering the dish with aluminum foil can prevent moisture loss and ensure even heating. Depending on the size of the casserole dish, reheating will take approximately 20-30 minutes. It’s always a good idea to check the internal temperature with a food thermometer.

pineapple casserole
Pineapple Cheese Casserole Recipe

Reheating from Frozen

For a frozen casserole, the best method is to plan ahead. Thaw it in the refrigerator the next day before reheating. If you’re in a hurry, use a microwave-safe dish to defrost it before baking. Increase the cooking time and lower the oven temperature to prevent the edges of the casserole from drying out while the middle heats up.

Speaking of frozen casseroles, I always like to recommend that any casseroles that are dairy-heavy should not be frozen. Casseroles with a lot of dairy products and creamy sauces don’t really tend to freeze well. You can definitely make these types of homemade casseroles a day or two ahead, though, and reheat them from refrigerated! It’s a great way to save time and plan ahead. Since I work from home, I often make our dinner casseroles early in the day, pop them in the fridge, and then heat them up for my family at dinnertime.

creamy green beans in a casserole dish
Classic Green Bean Casserole Recipe

What About Store-Bought Casserole?

The reheating method for store bought casseroles really varies from product to product. Refer to the package instructions and make sure that you heat the whole thing thoroughly according to the instructions on the specific product. I often place store-bought casseroles on a baking sheet in my oven to prevent spillage into the bottom of my oven should they bubble over the provided dish.

Should I Cover My Casserole When Re-heating?

Yes, you should generally cover your casserole with aluminum foil when reheating. This helps to retain moisture, ensuring the middle gets hot throughout without the top drying out. For a crispy topping, remove the foil for the last few minutes of reheating. You might even want to add some fresh toppings to your casserole at the end of the re-heating cook time. I’m talking extra cheese, of course!

Do I Need to Add Moisture When Re-heating My Casserole?

It depends on the type of casserole. For drier casseroles, like those containing rice or pasta, it’s a good idea to add a little bit of moisture. Drizzle some chicken broth or water around the edges of the casserole before covering it with foil to keep it from drying out. If it’s a creamy casserole made with dairy (sour cream, cream cheese, or other cream sauces), you may want to use a little milk to loosen the recipe up for better results when warming the casserole up in the oven.

doritos casserole
Dorito Casserole Recipe

Best Tips for Reheating Casseroles

  • Thawing: For the best results, especially with a frozen casserole, let it thaw to room temperature or in the refrigerator overnight. Having the patience to allow the casserole to thaw ahead of time will really improve your dinner-outcome.
  • Moisture: To prevent a dry casserole, consider adding a bit of moisture such as chicken broth or tomato sauce around the edges of the casserole before reheating.
  • Portion Size: If you’re reheating a large portion or the entire casserole, give it enough time in the oven. For smaller portions or single portions, a microwave oven, air fryer, or toaster oven can be a convenient way to reheat single servings of casserole.
  • Temperature: Use a moderate oven temperature to heat the casserole evenly. An oven method involving a preheated oven at 350°F usually yields the best results.
  • Safety: Always ensure that the internal temperature of the reheated casserole reaches a safe temperature of 165°F, as checked by an instant-read thermometer. You want to make sure that what you’re eating is not only delicious, but also safe.

See, reheating your casserole is a total snap! Now that you have the process down, be sure to explore this blog to find some new casserole recipes to try. After all, casseroles are easy-peasy and totally delicious!

Can I Reheat Casserole in an Air Fryer or Toaster Oven?

Yes and yes! Follow the same general principals as reheating your casserole in the oven. Portion small enough to fit in your air fryer or toaster oven, and use a heat-safe dish. Cover with foil. Use a temperature of about 300-350 and ensure that the internal temperature of your warmed-up casserole is 165°F, as checked by an instant-read thermometer. With an air fryer or toaster oven, it’s a check-and-see approach. Keep an eye on it!

​Our Favorite Casserole Recipes

Looking for some absolutely incredible casserole recipes to try? I recommend my Dorito Casserole, John Wayne Casserole, Cauliflower Casserole, and Jiffy Corn Casserole.

What’s your all-time favorite casserole recipe? I’d love to hear more about it in the comment section below!