Cheesy Mushroom Casserole

Name: Cheesy Mushroom Casserole
Prep time: 10 min
Cook time: 30 min
Total time: 40 min
Yield: 6 servings
Ingredients: ¼ cup olive oil; 32 ounces baby bella or crimini mushrooms; 2 teaspoons Diamond Crystal kosher salt; 1 cup onions; 1 tablespoon fresh garlic; ½ teaspoon black pepper; ½ teaspoon dried thyme; 1 cup gruyere cheese; 1 teaspoon dried parsley

User Reviews

5.0

144 reviews

Excellent

Prep Time
10 mins
Cook Time
10 mins
Total Time
40 mins
Servings
6 servings
Calories
200 kcal
Course
Side Dish
Cuisine
American

Cheesy Mushroom Casserole

Winston Campbell

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

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Ingredients

Servings

¼ cup olive oil plus more for the pan
32 ounces baby bella or crimini mushrooms sliced
2 teaspoons Diamond Crystal kosher salt or 1 teaspoon of any other salt, including Morton kosher 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

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Instructions

Preheat the oven to 400°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.

Notes

If your casserole dish is broiler-safe, instead of baking, 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.
A good way to vary this recipe is to use different cheeses, such as cheddar, Gouda, or provolone.
I use a lot of mushrooms - 32 ounces. But keep in mind that mushrooms lose significant volume after they are cooked. Once cooked, they fit nicely in a 2-quart casserole dish.
I like to use brown mushrooms because they make the casserole look more presentable than white mushrooms. So, I typically use baby Bella or crimini mushrooms.
Once the leftovers are cool, transfer them with a slotted spoon to an airtight container and keep them in the fridge for up to 4 days. Reheat them in the microwave at 50% power.