If you’re looking for the ultimate comfort-food dinner, this Creamy, Cheesy Chicken and Mushroom Spaghetti Casserole is a recipe worth keeping. Tender chicken, earthy mushrooms, perfectly cooked spaghetti, and a rich, creamy sauce are combined and baked beneath a golden layer of melted cheese.
It’s hearty enough for a family dinner, easy enough for a weeknight, and makes wonderful leftovers the next day. It’s also a great way to turn simple pantry ingredients into a warm and satisfying casserole.
Ingredients
For the Casserole
- 12 oz spaghetti
- 2 cups cooked chicken, shredded or chopped
- 2 cups sliced mushrooms
- 1 small onion, finely diced
- 3 cloves garlic, minced
- 2 tablespoons butter
- 1 tablespoon olive oil
- 1 can (10.5 oz) cream of mushroom soup
- 1/2 cup cream cheese, softened
- 1 cup milk
- 1/2 cup chicken broth
- 1/2 teaspoon Italian seasoning
- 1/2 teaspoon garlic powder
- 1/2 teaspoon onion powder
- 1/2 teaspoon paprika
- 1/2 teaspoon black pepper
- Salt, to taste
- 1 cup shredded mozzarella cheese
- 1 cup shredded cheddar cheese
- 1/3 cup grated Parmesan cheese
- 2 tablespoons chopped fresh parsley, optional
Instructions
1. Cook the Spaghetti
Preheat your oven to 375°F (190°C).
Bring a large pot of salted water to a boil. Cook the spaghetti according to the package directions, but stop cooking it about 1–2 minutes before it reaches al dente.
The pasta will continue cooking in the oven, so slightly undercooking it helps prevent mushy spaghetti.
Drain well and set aside.
2. Sauté the Mushrooms and Onion
Heat the butter and olive oil in a large skillet over medium heat.
Add the diced onion and cook for about 3 minutes until softened.
Add the mushrooms and cook for 5–7 minutes, stirring occasionally, until they release their moisture and begin to brown.
Stir in the minced garlic and cook for another 30 seconds.
3. Make the Creamy Sauce
Reduce the heat to medium-low.
Add the cream of mushroom soup, cream cheese, milk, and chicken broth to the skillet.
Stir until the cream cheese melts and the sauce becomes smooth and creamy.
Season with Italian seasoning, garlic powder, onion powder, paprika, black pepper, and salt.
Let the sauce gently simmer for 2–3 minutes. Avoid boiling it vigorously.
4. Add the Chicken
Stir the cooked chicken into the creamy mushroom sauce.
Allow everything to warm together for another 2–3 minutes.
Taste and adjust the seasoning if needed.
5. Combine With the Spaghetti
Add the cooked spaghetti to the skillet or transfer everything to a large mixing bowl.
Toss gently until the pasta is thoroughly coated with the creamy chicken and mushroom sauce.
Stir in half of the mozzarella and half of the cheddar for extra cheesiness throughout the casserole.
6. Assemble the Casserole
Lightly grease a 9 × 13-inch baking dish.
Transfer the spaghetti mixture into the dish and spread it into an even layer.
Sprinkle the remaining mozzarella and cheddar over the top.
Finish with the grated Parmesan.
7. Bake
Cover the casserole loosely with aluminum foil and bake for 20 minutes.
Remove the foil and continue baking for another 10–15 minutes, or until the cheese is melted, bubbling, and lightly golden.
For a more deeply browned top, place it under the broiler for 1–2 minutes at the end, watching carefully so the cheese doesn’t burn.
8. Rest and Serve
Remove the casserole from the oven and let it rest for about 5–10 minutes before serving.
Sprinkle with fresh parsley if desired.
Slice or scoop into portions and serve warm.
Tips for the Best Chicken Spaghetti Casserole
Don’t overcook the pasta: Slightly undercooked spaghetti holds its texture better after baking.
Brown the mushrooms: Allowing the mushrooms to cook until their excess moisture evaporates gives the casserole a deeper flavor.
Use freshly shredded cheese: It usually melts more smoothly than pre-shredded cheese.
Don’t make the sauce too thick: The pasta absorbs some of the sauce while baking. A slightly loose sauce helps keep the finished casserole creamy.
Let it rest: Giving the casserole several minutes to cool helps the sauce thicken slightly and makes serving easier.
Easy Variations
Add Bacon
Cook 5–6 slices of bacon until crisp, crumble them, and stir some into the filling. Sprinkle the rest over the cheese before baking.
Add Vegetables
Broccoli, spinach, peas, bell peppers, or diced zucchini can easily be added to the casserole.
Use Rotisserie Chicken
A store-bought rotisserie chicken makes this recipe especially quick. Simply remove the skin and bones and shred the meat.
Make It Spicy
Add red pepper flakes, diced jalapeños, or a pinch of cayenne pepper to the creamy sauce.
Extra Garlic
For garlic lovers, increase the fresh garlic to 4 cloves or add a small amount of roasted garlic to the sauce.
Make-Ahead Instructions
This casserole can be assembled ahead of time.
Prepare everything as directed, transfer it to the baking dish, and cover tightly. Refrigerate for up to 24 hours before baking.
When ready to bake, let the casserole sit at room temperature for about 15–20 minutes while the oven preheats. You may need to add several extra minutes to the covered baking time because the casserole will be cold.
Storage
Store leftover casserole in an airtight container in the refrigerator for 3–4 days.
Reheat individual portions in the microwave or reheat larger portions covered in the oven until hot throughout.
If the casserole seems dry after refrigeration, add a small splash of milk or chicken broth before reheating.
Can You Freeze It?
Yes. For best results, assemble the casserole without baking it and freeze it in a freezer-safe baking dish.
Cover tightly and freeze for up to 2–3 months.
Thaw overnight in the refrigerator before baking. Add a little extra sauce or milk if the pasta appears dry after thawing.
What to Serve With It
Because this casserole is rich and filling, it pairs beautifully with lighter sides such as:
- Crisp green salad
- Steamed broccoli
- Roasted green beans
- Garlic bread
- Sautéed vegetables
- Simple cucumber salad
Final Thoughts
This Creamy, Cheesy Chicken and Mushroom Spaghetti Casserole brings together everything you want in a cozy baked dinner: tender chicken, savory mushrooms, creamy sauce, perfectly cooked spaghetti, and plenty of bubbling cheese.
It’s easy to customize, perfect for using leftover chicken, and comforting enough for a family meal or weekend gathering. Once you try it, don’t be surprised if it becomes one of those recipes everyone asks you to make again.