Spinach Mushroom Chicken Alfredo Casserole – Creamy, Comforting, and Easy

This Spinach Mushroom Chicken Alfredo Casserole is the kind of weeknight dinner that feels special without a ton of effort. It’s creamy, cozy, and packed with flavor from tender chicken, earthy mushrooms, and a velvety Alfredo sauce. The spinach adds color and a fresh note, while a crispy topping brings the perfect crunch.

It’s familiar, crowd-pleasing, and great for leftovers. Whether you’re feeding a family or prepping meals for the week, this casserole delivers every time.

Spinach Mushroom Chicken Alfredo Casserole - Creamy, Comforting, and Easy

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Prep Time 15 minutes mins

Cook Time 30 minutes mins

Total Time 45 minutes mins

Servings 6 servings

Ingredients

  

• 10 ounces dried pasta (penne, rotini, or rigatoni work best)
• 2 cups cooked chicken, shredded or cubed (rotisserie is great)
• 8 ounces mushrooms, sliced (cremini or button)
• 3 cups fresh spinach (or 10 ounces frozen spinach, thawed and squeezed dry)
• 3 tablespoons unsalted butter
• 3 tablespoons all-purpose flour
• 2 cups whole milk (or 1 1/2 cups milk + 1/2 cup cream for richer sauce)
• 3/4 cup grated Parmesan cheese, plus extra for topping
• 1 cup shredded mozzarella (for topping and mixing)
• 2 cloves garlic, minced
• 2 tablespoons olive oil
• 1/2 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon black pepper
• 1/4 teaspoon crushed red pepper flakes (optional, for a little heat)
• 1/2 teaspoon Italian seasoning or dried oregano
• 1/3 cup panko breadcrumbs (optional, for crunch)
• Fresh parsley, chopped (optional, for garnish)

Instructions

 

• Preheat and prep: Heat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
• Boil the pasta: Cook pasta in salted water until just shy of al dente (about 1–2 minutes less than package directions). Drain and set aside.
• Sauté the mushrooms: In a large skillet, heat olive oil over medium-high. Add mushrooms and a pinch of salt. Cook, stirring occasionally, until they release liquid and brown, 6–8 minutes.
• Add garlic and spinach: Reduce heat to medium. Add garlic to the mushrooms and cook 30 seconds. Add spinach and cook until wilted. If using frozen spinach, stir in until warmed through.
• Make the Alfredo base: In a separate pot, melt butter over medium heat. Whisk in flour and cook 1 minute to form a roux.
• Build the sauce: Slowly whisk in milk, stirring constantly until smooth. Bring to a gentle simmer and cook 2–3 minutes until slightly thickened.
• Add cheese and season: Remove from heat. Stir in Parmesan, salt, pepper, red pepper flakes, and Italian seasoning. Adjust seasoning to taste.
• Combine everything: In a large bowl, mix pasta, chicken, mushroom-spinach mixture, and about two-thirds of the mozzarella. Pour over the Alfredo sauce and toss until evenly coated.
• Assemble the casserole: Transfer to the prepared baking dish. Top with remaining mozzarella, a sprinkle of Parmesan, and panko if using.
• Bake: Bake uncovered for 18–22 minutes, until bubbly around the edges and lightly golden on top.
• Finish and serve: Let it rest 5–10 minutes so it sets up a bit. Garnish with chopped parsley and serve warm.

What Makes This Recipe So Good

• Comfort food done right: Creamy Alfredo meets juicy chicken and savory mushrooms for a balanced, satisfying bite.
• Easy weeknight win: Uses simple ingredients and comes together with minimal fuss. You can even use rotisserie chicken.
• Make-ahead friendly: Assemble it in the morning, bake at dinner time.

  It also freezes well.

• Texture you’ll love: Creamy pasta and sauce under a golden, cheesy topping with a light crunch.
• Flexible and forgiving: Swap veggies, change the pasta, or lighten it up with a few quick tweaks.

What You’ll Need

• 10 ounces dried pasta (penne, rotini, or rigatoni work best)
• 2 cups cooked chicken, shredded or cubed (rotisserie is great)
• 8 ounces mushrooms, sliced (cremini or button)
• 3 cups fresh spinach (or 10 ounces frozen spinach, thawed and squeezed dry)
• 3 tablespoons unsalted butter
• 3 tablespoons all-purpose flour
• 2 cups whole milk (or 1 1/2 cups milk + 1/2 cup cream for richer sauce)
• 3/4 cup grated Parmesan cheese, plus extra for topping
• 1 cup shredded mozzarella (for topping and mixing)
• 2 cloves garlic, minced
• 2 tablespoons olive oil
• 1/2 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon black pepper
• 1/4 teaspoon crushed red pepper flakes (optional, for a little heat)
• 1/2 teaspoon Italian seasoning or dried oregano
• 1/3 cup panko breadcrumbs (optional, for crunch)
• Fresh parsley, chopped (optional, for garnish)

Instructions

1. Preheat and prep: Heat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
2. Boil the pasta: Cook pasta in salted water until just shy of al dente (about 1–2 minutes less than package directions). Drain and set aside.
3. Sauté the mushrooms: In a large skillet, heat olive oil over medium-high.

   Add mushrooms and a pinch of salt. Cook, stirring occasionally, until they release liquid and brown, 6–8 minutes.

4. Add garlic and spinach: Reduce heat to medium. Add garlic to the mushrooms and cook 30 seconds.

   Add spinach and cook until wilted. If using frozen spinach, stir in until warmed through.

5. Make the Alfredo base: In a separate pot, melt butter over medium heat. Whisk in flour and cook 1 minute to form a roux.
6. Build the sauce: Slowly whisk in milk, stirring constantly until smooth.

   Bring to a gentle simmer and cook 2–3 minutes until slightly thickened.

7. Add cheese and season: Remove from heat. Stir in Parmesan, salt, pepper, red pepper flakes, and Italian seasoning. Adjust seasoning to taste.
8. Combine everything: In a large bowl, mix pasta, chicken, mushroom-spinach mixture, and about two-thirds of the mozzarella.

   Pour over the Alfredo sauce and toss until evenly coated.

9. Assemble the casserole: Transfer to the prepared baking dish. Top with remaining mozzarella, a sprinkle of Parmesan, and panko if using.
10. Bake: Bake uncovered for 18–22 minutes, until bubbly around the edges and lightly golden on top.
11. Finish and serve: Let it rest 5–10 minutes so it sets up a bit. Garnish with chopped parsley and serve warm.

How to Store

• Refrigerate: Cool completely, then cover tightly.

  Store up to 4 days. Reheat covered at 350°F until hot, or microwave in portions.

• Freeze: Assemble but don’t bake, or freeze leftover portions. Wrap well with foil and plastic wrap.

  Freeze up to 2 months.

• Reheat from frozen: Thaw overnight in the fridge, then bake covered at 350°F for 25–35 minutes, uncovering at the end to re-crisp the top.

Health Benefits

• Protein-rich: Chicken provides lean protein for muscle repair and lasting fullness.
• Veggie boost: Spinach adds iron, vitamin K, and folate; mushrooms bring B vitamins and antioxidants.
• Balanced comfort: Pairing pasta with protein and veggies makes this more satisfying and steady on energy than a plain pasta dish.
• Customizable lighter options: You can cut saturated fat by using part-skim mozzarella and milk instead of cream, without losing the creamy feel.

Pitfalls to Watch Out For

• Soggy pasta: Don’t fully cook the pasta before baking. Slightly undercooked is best so it finishes perfectly in the oven.
• Watery sauce: If using frozen spinach, squeeze it very dry. Excess moisture can thin the Alfredo and dull the flavor.
• Bland sauce: Taste and season the Alfredo before mixing.

  Parmesan, salt, and pepper should be distinct but balanced.

• Overbaking: Too long in the oven can dry out the chicken and pasta. Pull it when it’s bubbling and lightly golden.
• Clumpy cheese: Take the sauce off heat before stirring in Parmesan. Overheating can make it grainy.

Alternatives

• Protein swaps: Use turkey, Italian sausage, or shrimp.

  For vegetarian, skip chicken and add more mushrooms or roasted cauliflower.

• Pasta options: Try whole-wheat pasta for more fiber, or gluten-free pasta if needed. Short, ridged shapes hold sauce well.
• Lighter sauce: Use 2% milk and part-skim mozzarella. Add a squeeze of lemon at the end to brighten the flavor.
• Dairy-free: Use olive oil instead of butter, a plant-based milk, and vegan Parmesan-style cheese.

  Thicken with a cornstarch slurry.

• Extra veggies: Stir in peas, steamed broccoli, or roasted red peppers for more color and texture.
• Herb and spice twist: Add fresh basil, thyme, or a pinch of nutmeg to the sauce for a classic Alfredo note.

FAQ

Can I use jarred Alfredo sauce?

Yes. Use about 24–26 ounces of a good-quality jarred Alfredo. Warm it gently and season to taste before mixing with the pasta and fillings.

Do I need to cook the chicken first?

Yes.

This recipe uses cooked chicken. Rotisserie chicken, leftover grilled chicken, or poached chicken all work well.

Can I make this ahead of time?

Absolutely. Assemble the casserole up to 24 hours ahead, cover, and refrigerate.

Add 5–10 extra minutes to the bake time since it will be cold.

What’s the best pasta for this casserole?

Short shapes like penne, rigatoni, or rotini are ideal. They trap sauce and bake evenly without turning mushy.

How can I prevent the sauce from separating?

Keep the heat moderate when making the roux and adding milk. Remove from heat before stirring in Parmesan and avoid boiling the finished sauce.

Can I add bacon?

Yes, and it’s delicious.

Cook until crisp, crumble, and fold it in with the chicken. Reduce added salt slightly since bacon is salty.

How do I make it spicier?

Increase the crushed red pepper flakes, or add a pinch of cayenne to the sauce. You can also stir in a spoonful of Calabrian chili paste.

Wrapping Up

This Spinach Mushroom Chicken Alfredo Casserole brings together simple ingredients for a meal that feels both comforting and fresh.

It’s easy to adapt, great for meal prep, and always welcome at the table. With a creamy sauce, hearty protein, and tender veggies, it checks all the boxes for a reliable, satisfying dinner. Keep this one in your rotation—you’ll reach for it again and again.