This is a baked spaghetti casserole built around shredded chicken, cream of mushroom soup, sour cream, diced tomatoes with green chilies, and two full cups of cheddar. It comes together in about an hour and feeds six — but the real reason to make it is that it reheats better than almost any other pasta dish, which means dinner tonight and easy lunches for the next two days.
What makes this version work
Two things matter here. First, cook the spaghetti just to al dente — not a minute past. It will keep cooking in the oven, and if it goes in soft, it comes out mushy. Second, sautéing the onion and garlic in butter before adding them to the mixing bowl is worth the extra pan. Raw onion baked into a casserole stays sharp and a little harsh; cooked onion melts into the sauce and rounds out the whole thing. Everything else is just assembly.
Ingredient notes
- Cream of mushroom soup (10.5 oz can): Use it straight from the can — do not dilute it. The undiluted soup is what gives the sauce enough body to coat the pasta without going watery in the oven.
- Diced tomatoes with green chilies (10 oz can, drained): Drain them well. Press the can lid against the tomatoes and tip out as much liquid as you can. Extra liquid is the main reason casseroles turn soupy.
- Rotisserie chicken: This is the easiest option and it works well. Pull it while it’s still warm — the meat shreds faster and more evenly than cold chicken. Two cups of shredded meat is roughly half of a standard store-bought bird, so you’ll have the other half left for something else.
- Smoked paprika: The recipe marks it optional, but skip the garnish instead — not worth the extra dish. Keep the paprika; it adds a low background warmth that plain paprika doesn’t.
Troubleshooting
- The casserole is watery after baking: Almost always caused by undrained tomatoes or spaghetti that wasn’t shaken dry after draining. Shake the colander well and press the tomatoes before mixing.
- The cheese on top is melted but not browned after 35 minutes: Ovens vary. Switch to the broiler for the last 2–3 minutes, watching closely. Pull it the moment the cheese gets color — it goes from golden to burnt fast.
- The pasta clumped together before it went into the bowl: Toss the drained spaghetti with a small drizzle of olive oil right after draining if you’re not mixing it immediately. It only takes about 30 seconds and stops the strands from sticking into a solid mass.
- Leftovers dried out when reheated: Add a tablespoon or two of water or chicken broth per portion before microwaving, then cover loosely. The pasta absorbs moisture as it sits, so it needs a little liquid added back to loosen up.
- The filling tastes flat: Taste the mixture in the bowl before it goes into the baking dish. Canned soups vary in saltiness by brand. If it needs more, add salt in small increments — a quarter teaspoon at a time — and stir before tasting again.
Creamy Baked Chicken Spaghetti
Equipment
- Large Pot
- Strainer
- Large mixing bowl
- Wooden spoon
- 9x13 inch baking dish
- Oven
Ingredients
- 12 oz spaghetti uncooked
- 2 cups cooked chicken shredded; rotisserie chicken works well
- 2 tablespoons unsalted butter
- 1 medium yellow onion finely chopped
- 2 cloves garlic minced
- 1 can cream of mushroom soup 10.5 oz can
- 1 can diced tomatoes with green chilies 10 oz can, drained
- 1 cup sour cream full-fat recommended
- 2 cups shredded cheddar cheese divided
- 1 teaspoon kosher salt adjust to taste
- 0.5 teaspoon black pepper freshly cracked
- 0.25 teaspoon smoked paprika optional but recommended
Instructions
- Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with oil or butter and set aside.
- Bring a large pot of salted water to a boil. Cook spaghetti until al dente according to the package instructions, about 8–10 minutes. Drain and set aside.
- While the pasta cooks, heat butter in a large pan over medium heat. Add finely chopped onion and cook for 5–7 minutes until soft and translucent. Stir in minced garlic and cook for another 30 seconds until fragrant, being careful not to burn it.
- In a large mixing bowl, combine the cooked onion and garlic, shredded chicken, cream of mushroom soup, drained diced tomatoes with chilies, sour cream, 1 cup of shredded cheddar, salt, pepper, and smoked paprika. Stir until well mixed.
- Add the cooked spaghetti to the bowl and toss until the pasta is thoroughly coated with the mixture.
- Transfer the spaghetti mixture into the prepared baking dish and top evenly with remaining 1 cup of shredded cheddar cheese.
- Bake uncovered for 30–35 minutes, or until cheese is melted, bubbling, and golden brown on top. Let rest for 5 minutes before serving.
Notes
- To make it spicier, use pepper jack cheese or add 1 finely chopped jalapeño to the onion sauté step.
- Substitute cream of chicken or cream of celery soup if you prefer a lighter mushroom flavor.
- Make this dish ahead up to the baking step, cover well, and refrigerate for up to 2 days before baking.
- If you're out of sour cream, substitute with Greek yogurt for a tangy alternative.
Nutrition
Frequently asked questions
Can I assemble this the night before and bake it the next day?
Yes — assemble the casserole fully, cover it tightly with foil, and refrigerate overnight. Add 10 minutes to the bake time since you’re starting from cold, and check that the center is hot all the way through before pulling it out.
Can I freeze this?
You can freeze it either before or after baking. Wrap the dish tightly in two layers of foil and freeze for up to two months. Thaw overnight in the fridge before baking or reheating — baking from frozen makes the texture uneven and the edges overcook before the center warms through.
What can I use instead of cream of mushroom soup?
Cream of chicken soup is the most straightforward swap and keeps the flavor profile close. Cream of celery also works if someone at the table dislikes mushrooms — it’s milder but still gives you the creamy, savory base the recipe needs.
How do I know when it’s done if I’m not sure about my oven?
The casserole is done when the cheese on top is bubbling at the edges and the center of the dish feels hot when you press it gently with the back of a spoon. If the top is browning too fast before the center heats through, tent it loosely with foil for the last 10 minutes.
What to cook next
- Creamy Fettuccine Alfredo
- Elegant Chicken Marsala with Mushrooms
- Sweet and Tangy Grape Chicken Salad
- Creamy Grape Salad with Southern Charm
