Mushroom Casserole - Healthy Recipes Blog (2024)

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Last updated: · Recipes developed by Vered DeLeeuw and nutritionally reviewed by Rachel Benight MS, RD · This website generates income via ads and uses cookies.

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This deliciously cheesy mushroom casserole is wonderfully flavored with onions, thyme, and melted gruyere.

Made without breadcrumbs and ready in about 40 minutes, it's keto and gluten-free.

Mushroom Casserole - Healthy Recipes Blog (1)

This casserole is amazing. It's so cheesy and flavorful! The wonderful aroma it releases when you cook it will let you know how good it's going to be.

Mushrooms are one of my favorite vegetables (well, technically they're fungi, not vegetables). And this tasty casserole is one of my favorite ways to cook them.

Jump to:
  • Ingredients
  • Instructions
  • Expert tip
  • Frequently asked questions
  • Variations
  • Serving suggestions
  • Storing leftovers
  • Related recipes
  • Foodie Newsletter
  • Recipe Card
  • Let's Connect

Ingredients

You'll only need a few simple ingredients to make this mushroom casserole. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:

Olive oil: A delicious oil and one of my favorites to cook with. It does have a relatively low smoke point, so you can use avocado oil instead.

Baby Bella mushrooms: You can also use white mushrooms if that's all you can find.

Salt and pepper: I use kosher salt in most of my recipes. If using fine salt, you will need to reduce the amount you use.

Aromatics: Onions and garlic. While jarred minced garlic is convenient, freshly minced tastes significantly better.

Spices: I use dried thyme and parsley.

Shredded Gruyere cheese: Gruyere tastes best, but I've made this casserole with shredded sharp cheddar and it was good too.

Mushroom Casserole - Healthy Recipes Blog (2)

Instructions

Since mushrooms release quite a bit of liquid when cooked, you can't just put them in a dish and bake them. You need to saute them first.

So to make this recipe, I saute the mushrooms and chopped onions in olive oil until the mushrooms have released their liquid and most of the liquid has evaporated.

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Check out the video below in the recipe card to see the process. See the steam? That's the mushroom's liquid, evaporating.

Once the liquid has mostly evaporated, you can transfer the mushrooms and onions to a greased baking dish, top them with cheese, and bake the casserole until the cheese has melted.

Mushroom Casserole - Healthy Recipes Blog (4)

Expert tip

If your casserole dish is broiler-safe, you can simply broil the casserole for 2-3 minutes, in the middle of the oven, until the cheese is melted. You don't want to get too close to the heating element and risk burning the casserole.

Frequently asked questions

What mushroom variety should I use?

I like to use brown mushrooms in this recipe because it makes the casserole look more presentable than white mushrooms. So I use baby Bella or crimini mushrooms.

I use quite a lot of mushrooms - 32 oz. But keep in mind that mushrooms lose significant volume after they are cooked. Once cooked, they fit nicely in a 2-quart casserole dish.

Since I'm lazy, I buy pre-sliced mushrooms at Whole Foods. I also buy pre-chopped onions. Which makes this casserole super easy!

What cheese is best in this casserole?

Gruyere goes wonderfully with mushrooms. But sometimes, when I have an open bag of pre-shredded Italian cheeses in the fridge, I use that instead.

Another tasty option is smoked gouda. It adds a wonderfully smoky flavor to the casserole.

Can I skip sauteing the mushrooms and simply bake them?

No, unfortunately, that won't work. As explained above, mushrooms release quite a bit of liquid when cooked, so you can't just put them in a dish and bake them. You need to saute them first and get rid of some of that liquid.

Variations

A good way to vary this recipe is by using different cheeses, such as cheddar, gouda, or provolone.

Another way is to experiment with different herbs and spices. Good options include smoked paprika, ground cumin, and dried oregano.

Serving suggestions

Mushrooms go well with steak, so I often make this recipe when I serve reverse-seared steak or London broil.

They are also excellent with chicken. Sometimes I slice baked chicken breast and top the slices with this casserole.

Since the mushrooms are not very colorful, it's nice to have a colorful veggie as a side, such as steamed broccoli or tomato salad.

Storing leftovers

Once the leftovers are cool, transfer them with a slotted spoon to an airtight container. Keep them in the fridge for up to 4 days. Reheat them in the microwave at 50% power.

Mushroom Casserole - Healthy Recipes Blog (5)
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Recipe Card

Mushroom Casserole - Healthy Recipes Blog (10)

4.99 from 447 votes

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Cheesy Mushroom Casserole

This deliciously cheesy mushroom casserole is wonderfully flavored with onions, thyme, and melted gruyere.

Prep Time10 minutes mins

Cook Time30 minutes mins

Total Time40 minutes mins

Course: Side Dish

Cuisine: American

Servings: 6 servings

Calories: 200kcal

Author: Vered DeLeeuw

Ingredients

  • ¼ cup olive oil plus more for the pan
  • 32 oz baby Bella or crimini mushrooms sliced
  • 2 teaspoons Diamond Crystal kosher salt or 1 teaspoon of fine salt
  • 1 cup onions chopped
  • 1 tablespoon fresh garlic minced
  • ½ teaspoon black pepper
  • ½ teaspoon dried thyme
  • 1 cup Gruyere cheese shredded
  • 1 teaspoon dried parsley for garnish

Instructions

  • Preheat your oven to 400 degrees F. Grease a 2-quart baking dish with olive oil.

  • Heat the olive oil in a large, deep skillet over medium-high heat. Add the mushrooms, onions, and kosher salt. Cook, stirring occasionally, until the mushrooms have released their liquid and the liquids have mostly evaporated, about 10 minutes.

  • Add the garlic, black pepper, and thyme. Cook, stirring, for one more minute. Remove from heat.

  • Transfer the mixture to the prepared baking dish. Sprinkle it with the shredded cheese.

  • Bake the casserole until hot and bubbly, about 15 minutes. Sprinkle with parsley and serve.

Video

Notes

If your casserole dish is broiler-safe, you can simply broil the casserole for 2-3 minutes, in the middle of the oven, until the cheese is melted. You don't want to get too close to the heating element and risk burning the casserole.

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Nutrition per Serving

Calories: 200kcal | Carbohydrates: 8g | Protein: 10g | Fat: 15g | Saturated Fat: 5g | Sodium: 441mg | Fiber: 2g | Sugar: 4g

Made this Recipe?

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Disclaimers

Cup measurements refer to the standard American cup, which is 240 milliliters. Most of my recipes are low-carb (or keto) and gluten-free, but some are not. Please verify that a recipe fits your needs before using it. Recommended and linked products are not guaranteed to be gluten-free. Nutrition info is approximate, and the carb count excludes non-nutritive sweeteners. Nutrition info may contain errors, so please verify it independently. Recipes may contain errors, so please use your common sense when following them. Please read these Terms of Use carefully before using any of my recipes.

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About the Author

Mushroom Casserole - Healthy Recipes Blog (21) Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. Click to learn more about Vered.

Reader Interactions

Comments

    Review this Recipe or Ask a Question:

  1. Lynn

    Mushroom Casserole - Healthy Recipes Blog (22)
    Who would have thought to combine cheese with mushrooms?!! But this works! We all enjoyed this as one of our sides for dinner guests; it was such a nice addition to other vegetables, in a non-competitive way. I used sliced portobello mushrooms which also gave a lovely flavour. Thank you..who would have thought?! 🙂

    Reply

    • Vered DeLeeuw

      I'm so glad you liked this recipe, Lynn! I love the idea of using portobello mushrooms.

      Reply

  2. Leslie

    Mushroom Casserole - Healthy Recipes Blog (23)
    Oh, Sooo Good!!

    Reply

    • Vered DeLeeuw

      Glad you liked it, Leslie!

      Reply

  3. Lynn

    Mushroom Casserole - Healthy Recipes Blog (24)
    Our love of mushrooms knows no bounds, so when we saw this recipe, we knew we had to try it at our pre-Christmas gathering and it was a hit! I didn't change a thing, assembled it early in the day and because oven space was at a premium, simply nuked it to melt the cheese and reheat the mushrooms; as a make-ahead dish...full marks! Thank you for publishing this yummy recipe!

    Reply

    • Vered DeLeeuw

      I'm so glad this recipe was a success, Lynn! It's interesting to learn that you can microwave it to melt the cheese. Thank you for this tip.

      Reply

  4. Patty

    Mushroom Casserole - Healthy Recipes Blog (25)
    I made this and it was a hit with my family. I’m going out of town and would like to bring this as a side dish. Can I make this, put it in a baking dish, refrigerate it and then bake it the next day? Thanks!

    Reply

    • Vered DeLeeuw

      Yes, absolutely. If I were you, I would pre-cook the mushroom/onion mixture (steps 2,3) and put it in a food storage container. Bring the shredded cheese in a separate bag or container. When ready to bake the casserole, grease the baking dish, assemble the casserole (drain any liquids from the mushroom/onion mixture before adding it to the baking dish), and bake it.

      Reply

  5. Lija

    Mushroom Casserole - Healthy Recipes Blog (26)
    I'm a mushroom lover, so I can't wait to try this recipe. I liked your tip to broil rather than bake the casserole for 2-3 minutes until the cheese is melted. I was thinking I could actually use my air fryer that's like a toaster oven instead of lighting the big oven.
    Also, since I always stir-fry mushrooms and onions when we have steak, I am looking forward to using this recipe when the husband grills steaks again. Thanks for the advice!

    Reply

    • Vered DeLeeuw

      You're very welcome, Lija! I hope you enjoy it.

      Reply

Mushroom Casserole - Healthy Recipes Blog (2024)

FAQs

What is the key to making a good casserole? ›

  1. Choose the right baking dish. If you're all about the crunchy topping, use a shallow dish. ...
  2. Undercook your pasta. ...
  3. Drain your meat. ...
  4. Beware of mushy vegetables. ...
  5. Know your cheeses. ...
  6. Master the art of casserole assembly. ...
  7. Don't skip the topping. ...
  8. Make it now, but bake it later.

How can I improve my casserole flavor? ›

Balance Flavors

Sweet, salty, spicy, and acidic elements should blend well and complement each other. Add ingredients like caramelized onions, olives, or lemon zest to give your casserole a depth of flavor.

How long to cook a frozen casserole? ›

Bake frozen, still covered in the foil, on the middle rack of a preheated 350°F oven until heated through, about 1 1/2 hours. Alternatively, thaw in the refrigerator overnight, then bake for only 1 hour.

Can you freeze a potato casserole? ›

In fact, casseroles are an excellent make-ahead meal because of how easy they are to prep, cook, freeze and store. The extra effort is minimal—you can double a recipe, freeze one and serve the other—and you're gifting yourself a mostly kitchen-free night at some point down the road.

Is it better to bake a casserole covered or uncovered? ›

In general, you'll want to bake a casserole covered with aluminum foil for most of the cooking time. Covering the casserole helps lock in moisture and prevents it from drying out. If you don't cover the casserole or uncover it too soon, the casserole will dry out.

What thickens a casserole? ›

The three main thickening agents for gravies are flour, cornflour and arrowroot. The first two are normally used in savoury dishes while arrowroot tends to be used in sweet dishes – that said, arrowroot will work in a savoury dish as it has no flavour.

How do you keep a casserole moist? ›

Pro Tip: Avoid Dry Casserole.

The best way to prevent it from drying out is to add a little bit of water, around ¼ cup, to the top of it. Allow the water to seep between the food and the sides of the baking dish. Cover with aluminum foil to seal in the moisture.

What temperature do you bake a casserole? ›

Again, any recipe will give you the oven temperature and baking time, but if you are making up your own casserole, don't cook it lower than 300 or higher than 400 degrees F. Casseroles generally do best at a moderately hot heat, especially if the ingredients are already cooked.

Is it better to freeze casseroles cooked or uncooked? ›

If your casserole has raw protein, like chicken or shrimp, make sure to bake it and cool it completely before freezing. If it doesn't have protein or the protein is cooked, no pre-baking is necessary.

Can I bake a frozen casserole without thawing? ›

Yes. It is safe to reheat frozen leftovers without thawing, either in a saucepan or microwave (in the case of a soup or stew) or in the oven or microwave (for example, casseroles and combination meals). Reheating will take longer than if the food is thawed first, but it is safe to do when time is short.

Can I put a frozen glass casserole dish in the oven? ›

When using Pyrex or any glass bakeware or cookware, you should avoid extreme temperature changes—very cold dishes shouldn't be placed in a hot oven, and vice versa. Sudden changes in temperature may cause the dishes to shatter or break.

What casseroles do not freeze well? ›

Yes, dairy-heavy casseroles are delicious, but cottage cheese, sour cream or creme fraiche won't hold up in the freezer.

What are the best potatoes to freeze? ›

Choose new, smaller potatoes of the waxy type such as red or gold potatoes. For best results, freeze as soon as harvested. Wash and scrub the potatoes leaving the skins on, if desired.

Can you freeze casseroles with mayo in them? ›

Casserole ingredients that won't freeze well

mayonnaise. eggs. starchy vegetables like potatoes. leafy greens.

What are the basics of a casserole? ›

There are 3 main parts that make up a casserole: the starchy base, the filling, and the sauce. The base: The starchy base is the foundation of the casserole. It isn't going to be the most flavorful part of the dish, but it is what will make the casserole filling and satisfying.

What are five basic components of most casseroles? ›

According to food blog High Heeled Homemaker, your basic casserole requires five ingredients: a protein, starch, vegetable, sauce, and cheese. If you have those five ingredients in your casserole dish, congratulations; you just made a casserole, whether it's a beloved recipe or a concoction of your own creation.

What is the best oven setting for casseroles? ›

Slow Cook

Another of the newer settings on electric ovens, this is characterised by a pot or casserole pot symbol. This symbol is designed to run on low consumption for low heat and very long cooking times. This is perfect for stews, casseroles and even some large meat BBQ like ribs and steaks.

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