Monterey Chicken Spaghetti

The first time I made this Monterey Chicken Spaghetti, my kitchen smelled like the inside of my favorite Italian-American restaurant. I had leftover rotisserie chicken and a random collection of cheese bits, so I threw them together with some spaghetti. My husband took one bite and asked why I never make this for dinner, as if it was something I had been keeping from him on purpose.

Last winter, my sister came over feeling completely overwhelmed by life, and I put this casserole in the oven while we sat at the counter talking. When it came out bubbling and golden, she actually teared up a little. Some nights, food is just what we need to feel like everything will be okay.

Ingredients

• 12 oz spaghetti: I learned the hard way that breaking spaghetti in half makes it much easier to toss evenly with the sauce
• 2 cups cooked chicken breast: Rotisserie chicken works beautifully here, but any leftover chicken breast or thigh meat will do
• 1 cup red bell pepper, diced: The sweetness of red peppers balances the rich cheese sauce perfectly
• 1 cup yellow onion, diced: Cook them until they are completely soft so they melt into the sauce
• 2 cloves garlic, minced: Add these after the vegetables soften so they do not burn and turn bitter
• 2 tbsp unsalted butter: This forms the base of your roux, so do not substitute with oil
• 2 tbsp all-purpose flour: Whisk constantly for a full minute to cook out the raw flour taste
• 2 cups whole milk: Warm milk creates a smoother sauce, but cold works if you whisk vigorously
• 1 cup Monterey Jack cheese, shredded: Buy a block and shred it yourself for better melting
• 1/2 cup sharp cheddar cheese, shredded: The sharpness cuts through the creaminess
• 1/2 cup low-sodium chicken broth: This adds depth without making the sauce too salty
• 1/4 cup sour cream: Stir this in at the very end to prevent curdling
• 1/2 tsp salt, 1/4 tsp black pepper, 1/4 tsp smoked paprika: The smoked paprika is the secret ingredient that makes people ask what you added
• 1/2 cup Monterey Jack cheese, shredded: Save this for the golden, bubbly topping
• 2 green onions, thinly sliced: These add a fresh bite against the rich cheese

Instructions

Get your oven ready:

Preheat to 375°F and grease a 9x13 baking dish with butter or cooking spray

Cook the spaghetti:

Boil in salted water until al dente, drain, and set aside while you make the sauce

Sauté the vegetables:

Melt butter in a large skillet, cook onions and bell peppers for 3 to 4 minutes until soft, then add garlic for 1 minute

Build the sauce base:

Stir in flour and cook for 1 minute, then gradually whisk in milk and chicken broth until smooth

Thicken it up:

Keep whisking for 3 to 4 minutes until the sauce coats the back of a spoon

Add the cheese:

Remove from heat, stir in Monterey Jack, cheddar, salt, pepper, and smoked paprika until melted and smooth

Combine everything:

Stir in sour cream, chicken, and cooked spaghetti until evenly coated

Assemble the casserole:

Transfer to your prepared dish and sprinkle the remaining Monterey Jack over the top

Bake until golden:

Slide into the oven for 20 to 25 minutes until bubbly and lightly golden on top

Finish and serve:

Garnish with sliced green onions right before serving while still hot

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This recipe has become my go-to for new moms and anyone who needs a meal they can just heat up. Last month I made three batches at once and froze them in disposable pans. The best compliment is when someone calls to ask for the recipe because their family keeps requesting it.

Make-Ahead Magic

You can assemble this casserole up to 24 hours ahead and refrigerate it unbaked. Add 5 to 10 minutes to the baking time since it will be cold. I have also frozen it for up to a month, wrapped tightly in foil and plastic.

Cheese Selection

Monterey Jack melts beautifully but I sometimes mix in pepper jack for a little kick. Just be careful with pre-shredded cheese since it often contains anti-caking agents that prevent smooth melting.

Serving Ideas

This casserole is quite filling on its own, but a crisp green salad with vinaigrette cuts through the richness. I also like to serve steamed broccoli or roasted asparagus on the side.

• Let the casserole rest for 10 minutes before serving
• The leftovers reheat surprisingly well in the microwave
• A glass of chilled Chardonnay pairs perfectly with the creamy sauce

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There is something deeply comforting about a bubbling cheese casserole coming out of the oven. This recipe has fed my family through busy weeknights, lazy weekends, and everything in between.

Recipe FAQs

→ Can I use rotisserie chicken for this dish?

Yes, rotisserie chicken works perfectly and saves time. Simply shred the meat and add it to the sauce mixture during step 6.

→ Can I make this ahead of time?

Absolutely. Assemble the casserole up to 24 hours in advance, cover tightly, and refrigerate. Add 5-10 minutes to the baking time if baking cold from the refrigerator.

→ What can I substitute for Monterey Jack cheese?

Colby, Pepper Jack for extra spice, or a Mexican cheese blend work well as substitutes. The flavor profile will shift slightly but remains delicious.

→ How do I store leftovers?

Store in an airtight container in the refrigerator for up to 4 days. Reheat in the microwave with a splash of milk to restore creaminess, or cover with foil and warm in a 350°F oven.

→ Can I freeze this casserole?

Yes, freeze before baking for best results. Wrap tightly in plastic and foil for up to 3 months. Thaw overnight in the refrigerator before baking as directed.

→ How do I prevent the sauce from separating?

Remove the skillet from heat before adding sour cream, and stir gently. Avoid boiling after adding dairy to maintain the sauce's smooth consistency.