Oven Baked Chicken Mushroom Cheese Casserole

When you need a warm, hearty dinner that everyone around the table will enjoy, this Oven Baked Chicken Mushroom Cheese Casserole is an excellent choice. Tender pieces of chicken are combined with golden mushrooms, sweet onion, fresh garlic, and a silky cream sauce before being covered with Parmesan and plenty of melted cheese.

As it bakes, the sauce becomes rich and creamy while the cheese melts into a golden, bubbling layer across the top. Every spoonful has tender chicken, flavorful mushrooms, creamy sauce, and gooey cheese. It is the perfect comfort food for a cozy evening and pairs wonderfully with simple sides.

Prep Time: 15 minutes
Cook Time: 35 minutes
Total Time: 50 minutes
Servings: 6
Cuisine: American / Comfort Food
Calories: Approximately 570 calories per serving

Ingredients

Main Ingredients

1.5 lbs boneless, skinless chicken breasts or thighs, cubed

8 oz fresh white button or cremini mushrooms, sliced

1 medium onion, diced

4 cloves garlic, minced

The Creamy Sauce Base

2 tablespoons butter

2 tablespoons olive oil, for searing

2 tablespoons all-purpose flour

1 cup chicken broth

1 cup heavy cream

The Cheeses & Garnish

1½ cups shredded Cheddar or Mozzarella cheese

½ cup grated Parmesan cheese

A small handful fresh parsley, finely chopped

Seasonings

1 teaspoon salt

½ teaspoon black pepper

1 teaspoon Italian seasoning, or a pinch of dried thyme

Instructions

Prepare the Chicken

Preheat the oven to 375°F (190°C).

Pat the cubed chicken dry with paper towels. Season with half of the salt and black pepper.

Heat the olive oil in a large oven-safe skillet over medium-high heat. Add the chicken and sear for several minutes, turning occasionally, until lightly golden on the outside.

The chicken does not have to be fully cooked because it will continue cooking in the oven. Transfer it to a plate and set aside.

Cook the Mushrooms and Aromatics

Add the butter to the same skillet and reduce the heat to medium.

Add the diced onion and cook for three to four minutes until softened.

Add the sliced mushrooms and cook for five to seven minutes. Let them release their moisture and develop some golden color.

Stir in the minced garlic and cook for approximately 30 seconds, until fragrant.

Make the Creamy Sauce

Sprinkle the flour over the mushroom mixture and stir continuously for about one minute.

Slowly add the chicken broth while stirring constantly. Continue stirring as the liquid is incorporated.

Pour in the heavy cream and stir until the sauce becomes smooth.

Add the remaining salt, black pepper, and Italian seasoning.

Allow the sauce to gently simmer for a few minutes until slightly thickened. Do not let it boil vigorously.

Combine Everything

Return the seared chicken and any juices from the plate to the skillet.

Stir gently until the chicken and mushrooms are evenly coated in the creamy sauce.

If you are not using an oven-safe skillet, transfer the mixture to a lightly greased casserole dish.

Spread everything into an even layer.

Add the Cheese

Sprinkle Parmesan evenly over the chicken mixture.

Cover the top with shredded Cheddar or Mozzarella.

Make sure the cheese reaches across most of the surface so it creates a rich, golden topping during baking.

Bake

Place the casserole in the preheated oven and bake uncovered for 20–25 minutes.

The casserole is ready when the chicken is cooked through and the cheese is melted, bubbling, and lightly golden.

For a deeper golden finish, broil for one to two minutes at the end, keeping a close eye on it.

Rest and Garnish

Remove the casserole from the oven and allow it to rest for approximately five minutes.

Scatter freshly chopped parsley over the top.

Serve warm with your favorite side dishes.

Tips

Sear the Chicken Properly

Patting the chicken dry before cooking helps it brown instead of steaming. Avoid overcrowding the skillet, as this can prevent the chicken from developing a flavorful golden exterior.

Take Your Time with the Mushrooms

Well-browned mushrooms add wonderful depth to the casserole. Cook them until their excess moisture has evaporated and their edges begin to turn golden.

Keep the Sauce Smooth

Add the broth gradually and stir continuously after adding the flour. This simple step helps prevent lumps and produces a smoother creamy sauce.

Do Not Boil the Cream Sauce Aggressively

A gentle simmer is enough to thicken the sauce. High heat can cause cream-based sauces to separate.

Grate Cheese Freshly When Possible

Freshly grated cheese usually melts more evenly. Mozzarella provides a mild, stretchy topping, while Cheddar adds more pronounced flavor.

Check the Chicken

Because chicken pieces vary in size, cooking time can vary slightly. The chicken should reach a safe internal temperature of 165°F (74°C).

Rest Before Serving

A short resting period allows the sauce to settle and makes the casserole easier to portion without the sauce immediately running across the plate.

Variations

Creamy Spinach Chicken

Add fresh spinach to the mushroom sauce and cook until wilted before returning the chicken to the skillet.

Chicken Mushroom Broccoli Casserole

Add cooked or lightly steamed broccoli florets to the casserole before adding the cheese. Cheddar works particularly well with this variation.

Italian-Style Chicken Casserole

Use Italian seasoning, Parmesan, mozzarella, and a little extra garlic. Fresh basil or parsley can be added after baking.

Spicy Chicken Mushroom Casserole

Add red pepper flakes, cayenne, or your favorite chili seasoning to the sauce for a spicy version.

Vegetable Loaded Version

Add sliced bell peppers, zucchini, spinach, or broccoli to increase the vegetable content and create an even heartier casserole.

Chicken Thigh Version

Use boneless, skinless chicken thighs for a richer and juicier result. Cut them into evenly sized pieces so they cook consistently.

Lighter Version

Replace some of the heavy cream with whole milk and use olive oil instead of some of the butter. The result will be lighter while remaining creamy.

Q&A

Can I use chicken breasts or thighs?

Both work well. Chicken breasts offer a leaner option, while boneless chicken thighs tend to stay particularly juicy and tender.

Can I use pre-cooked chicken?

Yes. If using cooked chicken, reduce the initial searing step and add the chicken when combining the sauce. Avoid baking it for too long so it does not become dry.

What mushrooms should I use?

White button and cremini mushrooms are excellent choices. Baby bella, shiitake, or mixed mushrooms can also be used.

Can I use half-and-half instead of heavy cream?

Yes. Half-and-half will create a lighter sauce. The finished casserole may be slightly less rich and thick.

Can I make this without flour?

You can use cornstarch as an alternative thickener. Mix a small amount with cold broth or water first to create a slurry before adding it to the sauce.

What should I serve with chicken mushroom casserole?

Crusty bread, mashed potatoes, roasted potatoes, rice, pasta, steamed vegetables, or a fresh green salad are all delicious options.

How long will leftovers last?

Keep leftovers refrigerated in an airtight container and consume within about three days.

Can I freeze the casserole?

Yes, although the texture of the cream sauce may change slightly after freezing and thawing. Cool completely before freezing and thaw overnight in the refrigerator before reheating.

Nutrition

Approximate nutrition per serving:

Calories: 570 kcal
Protein: 42 g
Fat: 38 g
Saturated Fat: 19 g
Carbohydrates: 12 g
Fiber: 1 g
Sugar: 4 g
Sodium: 850 mg

Nutrition information is estimated and may change depending on the exact ingredients, brands, cheese, cream, and portion sizes used.

Conclusion

Few things are more comforting than a bubbling casserole fresh from the oven, and this chicken and mushroom version delivers plenty of cozy flavor. The creamy sauce brings the chicken and mushrooms together, while Parmesan and melted Cheddar or Mozzarella create a deliciously cheesy finish.

Whether you are cooking for your family, preparing a satisfying Sunday dinner, or simply craving something creamy and hearty, this casserole is an easy recipe to keep in your rotation. Serve it with warm bread or your favorite side dish and enjoy a comforting homemade meal straight from the oven.

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