Parmesan Mushroom Casserole

This parmesan mushroom casserole is packed with flavorful mushrooms and cheesy goodness. It’s the perfect dish to make for a cozy night in or to take to your next potluck. And it’s so easy to make, you’ll be surprised how quickly it comes together.

You won’t be able to resist the creamy, dreamy texture of this casserole. The parmesan cheese adds a delicious depth of flavor that takes this dish over the top. And the mushrooms are just heavenly.

If you want a main dish with mushrooms, check out the creamy mushroom casserole with pasta. It's a great dish to serve as a meat-free meal.

blue plate of pasta with mushrooms on gray table

What Does Mushroom Casserole Go With?

This casserole goes great with a simple green salad or veggies like Brussels sprouts, asparagus, or green beans. It can even be paired with a cheesy gnocchi casserole or a side of healthy broccoli casserole for a full meal.

It can also be served as a side dish with roasted chicken or steak. Pork chops or a pork loin is also another great choice. I also love to pair this recipe with burgers, pasta, or seafood like shrimp. But it’s also delicious on its own or just served with a side of some crusty bread.

black baking dish of parmesan mushroom casserole with gold spoon in side

Ingredients

For the Casserole

4 tablespoons butter (56.8g)
1 medium white onion, sliced
3 garlic cloves, minced
1 teaspoon dried thyme (1g)
1 pound cremini mushrooms, sliced (500g)
1 pound oyster mushrooms, sliced (500g)
4 tablespoons all-purpose flour (31g)
⅔ cup heavy cream (227g)
½ cup sour cream (123g)
¼ cup grated Parmesan (22.5g)
1 teaspoon salt (6g)
½ teaspoon black pepper (1.5g)

For the crust

½ cup Panko breadcrumbs (50g)
3 tablespoons grated Parmesan (16.9g)
2 tablespoons butter, melted (28.4g)

mushrooms on cutting board with bowls of sauce and spices

Kitchen Tools Used

black and white oval baking dish of parmesan mushroom casserole

How to Make Parmesan Mushroom Casserole

Before you begin cooking, I recommend you start by prepping the vegetables. Chop, slice, or mince as directed and have everything ready so you can just grab and put it into the pan as needed. You can also pre-measure the rest of the ingredients if desired.

Then, you will preheat the oven to 375°F/190°Cand spray the baking dish with non-stick spray. I used a 10" oval casserole, but you can use a 9"x9" or a 9"x13" if you prefer.

Now you will begin cooking the mushroom cream mixture. Start by melting the butter in a large skillet over a medium heat setting. Then, add the chopped onions to the skillet and cook them for around 3 minutes, making sure that you stir them regularly. They should just begin turning soft.

Then, you will add the mushrooms into the skillet in batches. Add ⅓ of the mushrooms and cook them for around 5 minutes, until they have reduced significantly. Repeat this with the second ⅓ of the mushrooms.

Then, again, with the last of the mushrooms, except with the last batch, continue cooking the mixture for another 10 to 15 minutes. This step is where you want the mushrooms to shrink and the liquid to evaporate. It is also where the mushrooms will begin browning and get color.

Add the minced garlic, dried thyme, salt, and pepper to the mushrooms and stir well. Then, add in the 4 tablespoons of all-purpose flour and stir to coat everything. Let it cook for 1 minute.

Now, stir in the heavy cream and sour cream and bring it to a simmer. You want the mixture to begin bubbling, but be careful that it isn't curdling or burning.

cream being poured into skillet with cooked mushrooms

As soon as it begins bubbling, you will add in the sour cream and parmesan cheese. Once this is stirred and combined into a thick sauce mixture, remove the skillet from the heat source.

Now, pour the mushroom cream mixture into the prepared baking dish.

In a small bowl, mix together the Pank, parmesan, and butter to make the crunchy top.

Spread the crumbs over the top of the mushroom mixture and bake for 20 minutes.

gray table under blue bowl of pasta with mushrooms

Frequently Asked Questions

What Mushrooms Are Best for a Casserole?

I am using cremini and oyster mushrooms for this recipe. While these are my mushrooms of choice, you can use other mushrooms. Just make sure they are good-quality mushrooms.

If you can’t find cremini or oyster mushrooms, you can use white button mushrooms, baby Bella mushrooms, or even portobello mushrooms. Just make sure to chop them all into even small pieces so they cook well.

How Do I Clean Mushrooms?

Cleaning mushrooms is really easy. Just take a damp paper towel and lightly wipe off the mushrooms. You don’t need to wash them with water because they will absorb too much water and become mushy.

If you are using wild mushrooms, you may need to give them a little more attention. Just give them a light brush with a soft brush to remove any dirt that is in clumps before you wipe them with a paper towel.

How Long is Parmesan Mushroom Casserole Good For?

This casserole can be stored in the fridge for up to four days. Just make sure to store it in an airtight container, once it has cooled, so the cheese sauce doesn’t dry out.

Can I Freeze Mushroom Casserole?

Yes, this casserole can be frozen. You can freeze it as a whole casserole in a disposable pan, or in individual servings.

No matter which method you choose, make sure that you have wrapped it well in plastic wrap or aluminum foil if it is not in an airtight container. Then, label the casserole and date it so you know what it is once frozen. It keeps for up to 3 months in the freezer.

To thaw, just place the casserole in the fridge overnight. Then reheat in a 350-degree oven until warmed through.

parmesan mushroom casserole in baking dish sitting on top of cutting board

More Easy Casserole Recipes

Whether you are looking for another side dish, a meat-free option, or an entree, casseroles are the way to go. Below are some of our favorites that are sure to be a hit with everyone at your dinner table. Make sure that you bookmark these recipes, print out the recipes, or pin them to a casserole board on Pinterest so they are handy when you are ready to cook!

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