Creamy Chicken Spaghetti Casserole

This creamy chicken spaghetti casserole turns everyday ingredients into a baking dish of comfort that does not ask much of you on a weeknight. The pasta soaks up a rich sauce while the top gets bubbly and golden, and it all comes together with almost no hands-on time.

If you have leftover chicken or a rotisserie bird waiting in the fridge, this is the dinner that puts it to work in the best way.

Why This Casserole Works

The sauce stays silky instead of breaking because sour cream and cream of chicken soup hang onto moisture through the bake. Every forkful has tender spaghetti, shreds of chicken, and just enough salty bite from Parmesan.

The mozzarella on top actually browns into a thin, crackly crust while the inside stays soft. It is the kind of dish that tastes like you worked harder than you did, which is what a weeknight casserole should do.

Ingredients

• 8 oz spaghetti: broken in half so it mixes easily with the sauce
• 2 tbsp butter: for cooking the onion
• ½ cup finely chopped yellow onion: white onion works too
• 2 cups shredded cooked chicken: a rotisserie chicken makes prep faster
• 1 can (10.5 oz) cream of chicken soup: the base of the sauce, use regular or reduced-sodium
• 1 cup sour cream: full-fat gives the richest texture
• ½ cup chicken broth: keeps the pasta from soaking up too much liquid
• ½ cup grated Parmesan cheese: adds a salty, nutty layer in the sauce
• 1 tsp garlic powder
• ½ tsp onion powder
• ½ tsp salt: adjust if your broth or soup is already salty
• ¼ tsp black pepper
• 2 cups shredded mozzarella cheese: for the bubbling golden top

Variations / Substitutions

• Use turkey instead of chicken: Leftover roasted turkey or ground turkey sautéed until cooked through both work well.
• Swap the soup: Cream of mushroom or cream of celery soup stand in nicely if that is what you have.
• Add a vegetable: Stir in 1 cup of steamed broccoli florets or thawed frozen peas when you combine the pasta and sauce.
• Make it dairy-free: Use dairy-free sour cream, a plant-based cream of chicken soup alternative, and your favorite meltable dairy-free mozzarella.
• Change the cheese: A sharp white cheddar or provolone on top gives a different pull and tang.

For a stovetop take on the same flavors, try the quick Creamy Chicken and Noodles recipe.

How To Make Creamy Chicken Spaghetti Casserole

Step 1: Cook the Pasta and Sauté the Onion

Bring a large pot of salted water to a boil and cook the 8 oz spaghetti until just al dente, about 8 minutes. Drain it well and set it aside; you want it slightly firm so it holds its shape through baking.

While the pasta cooks, melt the 2 tbsp butter in a skillet over medium heat. Add the ½ cup chopped onion and cook, stirring now and then, for about 5 minutes, until the pieces are soft and translucent. The onion should smell sweet and mellow, not browned.

Step 2: Whisk the Creamy Sauce

Take the skillet off the heat and add the can of cream of chicken soup, 1 cup sour cream, ½ cup chicken broth, ½ cup grated Parmesan, 1 tsp garlic powder, ½ tsp onion powder, ½ tsp salt, and ¼ tsp pepper. Whisk everything together until the mixture is completely smooth and no streaks of sour cream remain.

Set the skillet over low heat and stir the sauce for about 2 minutes, just until it is warm and loosened. Then fold in the 2 cups shredded chicken and turn off the heat.

Step 3: Toss the Spaghetti with the Sauce

Add the drained spaghetti straight into the skillet of sauce. Using tongs or two big spoons, toss it all together for about 1 minute until every strand is coated and the chicken is evenly distributed. The sauce will look thick and cling well to the pasta.

At this point the mixture smells deeply savory, and you can taste a noodle to check if it needs a pinch more salt before baking.

Step 4: Bake the Casserole

Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish, then scrape the spaghetti mixture into the dish and spread it into an even layer. Scatter the 2 cups of shredded mozzarella evenly over the top.

Bake for 20 minutes, until the sauce is bubbling around the edges. Switch the oven to broil and cook for 2 to 3 minutes more, watching closely, until the cheese is puffed and golden brown in spots. The top should look blistered and irresistible.

Step 5: Scoop and Serve

Remove the dish from the oven and let the casserole rest on the counter for about 5 minutes. This brief wait helps the sauce set just enough so it does not run onto the plate.

Spoon generous portions into shallow bowls and serve while the cheese is still stretching. The contrast between the crunchy top and the creamy interior is what makes this dish a repeat request.

Tips for the Creamiest Casserole

• Do not overcook the pasta.: Boil it a full minute less than the package says so it can finish softening in the oven without turning mushy.
• Use freshly shredded mozzarella.: Pre-shredded cheese is coated in anti-caking agents that can keep it from melting into that silky, stretchy top.
• Let the dish rest before scooping.: A five-minute rest is enough for the sauce to thicken slightly, making each serving hold together better.
• Shred your own chicken.: A rotisserie bird is fast, but if you poach and shred a couple of boneless thighs, the meat stays especially moist.

Bake times by dish size:

Storing Leftover Casserole

• Refrigerate: Cover the cooled baking dish tightly or transfer portions to an airtight container. It keeps well for up to 4 days.
• Reheating: Microwave individual servings until hot, or warm the whole dish in a 350°F oven for about 15 minutes. Add a splash of broth if the pasta looks dry after storage.

What To Serve With Creamy Chicken Spaghetti Casserole

A crisp green salad with a sharp lemon vinaigrette cuts through the richness of the sauce and cheese. Roasted broccoli or steamed green beans tossed with a little garlic butter also work, because the bright green color and snap contrast nicely with the soft pasta. For something very simple, plain garlic bread is always welcome to catch any leftover sauce on the plate.

Frequently Asked Questions

Can I assemble this casserole the night before?

Yes. Assemble the dish up to the point of baking, cover it, and refrigerate. The next day, bake it straight from the fridge, adding about 10 extra minutes to the oven time to heat it through.

Can I freeze this casserole?

You can. Assemble it without baking, wrap the dish tightly, and freeze for up to 2 months. Thaw overnight in the fridge, then bake as directed, adding a few minutes until bubbly. The texture will be slightly softer, but it still tastes good.

My casserole turned out dry. What went wrong?

The most common reason is overcooking the spaghetti or using too little sauce. Make sure to cook the pasta just to al dente and measure the broth and sour cream carefully so there is enough liquid to steam inside the dish.

Can I use a different pasta shape?

Yes, penne, rotini, or medium shells all hold the sauce well. Just cook them to a firm al dente according to the package and use the same weight.