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How to Reheat a Frozen Casserole

Wondering how to reheat a frozen casserole for the best results? You have options of course, but choosing the best way to go comes down to a few hard and fast choices.

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Best Ways To Reheat Frozen Casseroles

When it comes time to reheat a frozen casserole, then first things first. Make sure you can do it in the first place. I know that sounds sort of counterintuitive, but seriously, look at the frozen casserole.

Did it sit too long in the freezer and have freezer burn? Was it stored poorly? If so, then better safe than sorry. Best not to waste your time reheating the casserole if it is just freezer burnt and doesn’t even resemble a piece of leftover casserole right? Toss it if you think it has been in there too long.

Hopefully you marked the container with a “use by” date. If not, then hope you have an amazing faculty for remembering what you had for dinner two months previously.

dish of ratatouille in a freezer

Handy Tips

If you plan on freezing a leftover casserole, then planning ahead helps. Here are more suggestions for best results reheating casseroles:

  • Make sure to start things off the right way. If you need to freeze your leftover cooked casserole, then divide it into portions first. Ideally, wrapping each piece separately in plastic wrap is best. But, if that isn’t possible, then just making portions that fit into a single airtight container works too.
  • Mark a date that it starts in the freezer and include a “use by” date too. Generally speaking, a casserole stores up to two months in a frost free freezer. A piece masking tape and a permanent marker do the trick.
  • Ideally, give yourself time to thaw the casserole in the fridge before reheating it. This allows excess moisture to either separate out or absorb back in.
  • You don’t need to bring the casserole to room temperature before heating. Just be sure it’s not frozen solid.
  • Decide on what is best first, a microwave, oven, or in a pan on the stove. All have their advantages and disadvantages based on what type of casserole you reheat.

Can I cook a frozen casserole without thawing?

You certainly can, but I recommend thawing the casserole overnight in the refrigerator before reheatings.

This allows all the layers to defrost and reheat evenly. Otherwise you might have a cold center while the outer edges burn and dry out.

single serve of lasagna over a freezer drawer

Best Ways to Reheat a Frozen Casserole

Do you want to use a microwave or a stove top or a toaster oven? What about using an air fryer to reheat a frozen casserole? Each has pluses and minuses.

A microwave is fast, but it can change the texture of certain ingredients, especially veggies. So, things like bell peppers don’t do well in the microwave, but others are fine, like potatoes.

Place the casserole in the microwave and use a medium high setting. Many actually have a reheat setting that is basically medium high for 10 minutes. You might need to turn the dish one or twice to ensure even cooking.

Be sure to use a microwave safe dish when reheating if the original baking dish is not.

Can you put a frozen casserole in the oven?

A stove top works well too. Cast iron fry pans that you can cover are ideal since they heat very evenly. In many cases, using medium high heat, you might reheat just as quickly this way as using a microwave.

Just remove the casserole from the baking dish and place in the skillet. Heat on medium until warmed through. You might need to add a small amount of water or broth if it gets dry.

An oven, or even a counter top toaster oven, yields the best results but has the longest cooking time. Heat the oven to 275F – 350 degrees Fahrenheit. and place the casserole in the oven. Cook until the internal temperature reaches at least 160F.

My instant read thermometer comes in handy in this instance.

Air fryers can also reheat leftover casserole servings. Make sure there is plenty of room for the hot air to circulate. Convection cooking is fast but make sure to not overcook it.

If you love this recipe as much as I do, pin this to your favorite casserole Pinterest board and share it on your favorite social media channels!

casserole dish with two hands over a freezer drawer with text "how to reheat a frozen casserole"

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