Easy Chicken Spaghetti Casserole With Creamy Cheese Sauce
Chicken spaghetti casserole is a practical way to turn cooked chicken into a full dinner. The spaghetti finishes cooking in a creamy sauce with onion, bell pepper, and cheese, so the chicken needs only enough oven time to heat through. This version uses a quick homemade sauce rather than condensed soup, with a soup substitution if that is what you have on hand.
The detail that matters most is the pasta. Boil it until it is still firm in the center, then give it enough sauce to finish cooking in the oven. Fully cooked spaghetti can turn soft during baking, especially if the casserole is assembled ahead.
Chicken Spaghetti Casserole Recipe
Yield: About 6 servings
Prep time: 20 minutes
Cook time: About 35 minutes, including baking
Total time: About 55 minutes
Course: Main dish
Cuisine: American
Equipment
- Large pot
- Colander
- Large skillet or saucepan
- 9-by-13-inch baking dish
Ingredients
- 12 ounces (340 g) dry spaghetti
- 2 tablespoons (28 g) unsalted butter
- 1 medium yellow onion, diced, about 1 cup (150 g)
- 1 medium bell pepper, diced, about 1 cup (150 g)
- 2 garlic cloves, minced
- 3 tablespoons (24 g) all-purpose flour
- 2 cups (475 ml) low-sodium chicken broth
- 1 cup (240 ml) whole milk
- 4 ounces (115 g) cream cheese, cut into pieces
- 2 cups (about 225 g) shredded sharp cheddar cheese, divided
- 3 cups (about 420 g) cooked, shredded or chopped chicken
- ½ teaspoon kosher salt, plus more for the pasta water and to taste
- ½ teaspoon freshly ground black pepper
- ½ teaspoon paprika
Instructions
Heat the oven and prepare the dish. Heat the oven to 375°F (190°C). Lightly grease a 9-by-13-inch baking dish.
Undercook the spaghetti. Bring a large pot of salted water to a boil. Add the spaghetti and cook it about 2 minutes less than the package’s al dente time. It should bend easily but still have a firm center when bitten. Before draining, reserve 1 cup (240 ml) of the pasta water. Drain the spaghetti.
Cook the vegetables. While the pasta boils, melt the butter in a large skillet or saucepan over medium heat. Add the onion and bell pepper. Cook, stirring occasionally, until softened, about 5 to 7 minutes. Add the garlic and cook for about 30 seconds.
Make the sauce. Sprinkle the flour over the vegetables and stir for 1 minute. Gradually pour in the chicken broth, stirring to work out any lumps, then add the milk. Bring the mixture to a gentle simmer and cook, stirring, until it thickens enough to lightly coat a spoon, about 3 to 5 minutes.
Add the cheese and chicken. Reduce the heat to low. Stir in the cream cheese until melted, then add 1½ cups (about 170 g) of the cheddar. Stir until smooth. Add the chicken, salt, pepper, and paprika. Taste the sauce and adjust the salt if needed.
Combine and bake. Add the drained spaghetti to the sauce and toss thoroughly. The mixture should look quite saucy; the pasta will absorb liquid as it bakes. If it seems stiff or difficult to toss, stir in reserved pasta water a little at a time. Transfer to the baking dish and sprinkle with the remaining ½ cup (about 55 g) cheddar. Bake uncovered for 20 to 25 minutes, until the edges are bubbling and the center is hot. Let stand for 5 minutes before serving.
Getting the Pasta and Sauce Right
Package directions are a better guide than a fixed boiling time because spaghetti thickness varies. For this casserole, start with the package’s al dente time and stop about 2 minutes early. The noodles continue to cook in the sauce during baking. If they are already soft when drained, they are likely to be softer still by the time the cheese topping melts.
The sauce should also look looser than a sauce meant for pasta served straight from the skillet. Spaghetti absorbs moisture in the oven and continues to absorb it while the casserole stands. Reserved pasta water is useful for loosening the mixture without adding more dairy. Add only enough that the noodles are coated and easy to move through the sauce; liquid should not pool in the baking dish.
Shredded chicken mixes evenly into the spaghetti, while chopped chicken gives you more distinct pieces. Either works. Rotisserie chicken and leftover roasted or poached chicken are convenient choices. Remove skin and bones, and break up any large pieces before adding the meat to the sauce. Because the chicken is already cooked, a long bake will not improve it. Coating it in sauce before baking and taking the casserole out once the center is hot help keep it moist.
The salt needed will depend on the broth, cheese, and chicken. Rotisserie chicken can be well seasoned, while home-cooked chicken may need more salt. Taste the sauce after adding the chicken, before it goes into the baking dish.
Substitutions That Work
The onion and bell pepper give this chicken spaghetti its familiar savory base, but there is room to adjust the vegetables. Diced celery can replace some of the bell pepper. For a little heat, use a can of diced tomatoes with green chiles in place of the bell pepper. Drain the tomatoes well so they do not thin the sauce. Cooked mushrooms also work, provided they have released most of their moisture before you add the flour.
Sharp cheddar gives the sauce a pronounced cheese flavor. Monterey Jack melts smoothly and can replace part of the cheddar if you prefer a milder casserole. Pre-shredded cheese will work, though cheese shredded from a block generally melts more smoothly. Keep the cream cheese if possible: it gives the sauce body without requiring a long simmer.
Using condensed soup instead of homemade sauce
For a shortcut, omit the butter, flour, broth, milk, and cream cheese. Cook the onion, bell pepper, and garlic in a little oil, then stir in two 10.5-ounce (298 g) cans of condensed cream of chicken soup and 1 cup (240 ml) milk. Add 1½ cups (about 170 g) cheddar, followed by the chicken and seasonings. Toss with the undercooked spaghetti and bake as directed, adding a splash of reserved pasta water if the mixture is too thick.
Condensed soup varies considerably in saltiness. Taste the mixture before adding any salt, and use less than the recipe calls for if the soup and chicken are already seasoned. Cream of mushroom soup can be used the same way, though it will change the flavor.
Make-Ahead, Freezing, and Leftovers
For a make-ahead dinner, assemble the casserole in its baking dish, cover it, and refrigerate it for up to 24 hours. The spaghetti will absorb some sauce while it sits. Before baking, check whether the mixture looks dry and stir in a little milk or broth if needed. Bake it covered at 375°F (190°C) until the center is hot, then uncover it for the last several minutes to melt the topping. A cold casserole will take longer than one assembled just before baking; use the temperature at the center rather than the clock as your guide.
Chicken spaghetti can also be frozen before baking. Assemble it in a freezer-safe dish, wrap it tightly, and freeze for up to 2 months for best quality. Thaw it in the refrigerator before baking. Because pasta softens during freezing and reheating, undercooking the spaghetti is especially useful here. Do not put a frozen glass baking dish directly into a hot oven; follow the dish manufacturer’s instructions for temperature changes.
Refrigerate cooked leftovers promptly in a covered container and use them within 3 to 4 days. Reheat individual portions with a spoonful of milk or broth, covered, until hot throughout. The added liquid loosens the sauce as the pasta warms.
A Creamy Dinner Built Around Cooked Chicken
This casserole works best when the spaghetti goes into the oven slightly underdone and generously coated with sauce. The chicken is already cooked, so the bake is brief: long enough to heat the center and melt the cheddar on top. With those two details in place, leftover chicken becomes a creamy, cheesy spaghetti dinner without drying out in the oven.
