Cheesy Chicken Spaghetti Casserole has become my most reliable weeknight dinner for good reason. The sauce is rich and creamy with just enough tang from the Rotel tomatoes to keep every bite interesting. Tender chicken, soft mushrooms, and cheddar and mozzarella are melted into every single bite. That cheesy, golden bubbly top? It honestly never lasts past dinner.
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It’s my go-to weeknight casserole when I need something hearty and crowd-pleasing, the kind of dish nobody ever turns down. This is also one of the best dishes to bring to a potluck or family gatherings because it travels well, reheats beautifully, and feeds a large group without any fuss. Leftovers keep well in the fridge for 3 to 4 days or freeze well for 2 to 3 months.
Ingredients You’ll Need
You’ll need all the ingredients shown in the photograph below.
How to Make Cheesy Chicken Spaghetti Casserole with Step-By-Step Instructions
Scroll down for the full recipe card containing a full printable recipe and measurements in both US customary and metric units.
Let me walk you through every step so you end up with a casserole that’s saucy, cheesy, and perfectly baked every single time.
Brown the Chicken
Heat 2 tablespoons of olive oil in a large skillet over medium heat and add your cubed chicken breasts. Cook for 7 to 10 minutes, turning occasionally with silicone-tipped tongs, until the pieces are golden on the outside and fully cooked through. Set the chicken aside on a plate while you get everything else going.
Cook the Spaghetti
Bring a large pot of salted water to a boil and cook your 8 ounces of spaghetti pasta according to the package directions until just al dente. You want it slightly undercooked here because it’s going to finish in the oven. Drain using a stainless steel colander and set aside.
Build the Sauce
In the same skillet you used for the chicken, melt the butter over medium heat. Add the diced onion and minced garlic and sauté until soft, then add the sliced mushrooms and cook for 2 more minutes.
Stir in the flour and cook for 1 to 2 minutes until it turns lightly golden. Gradually whisk in the chicken broth, then add the Rotel tomatoes and heavy cream. Let everything cook together until the sauce thickens.
Season with salt and black pepper, then stir in half of the sharp cheddar cheese and mozzarella cheese until the sauce is smooth and glossy. I use a box grater to shred them fresh right into the sauce, because using pre-shredded cheese won’t give you the same smooth melt. You may add or swap in Parmesan cheese, too.
SERIOUSLY GOOD
CASSEROLES
37 EASY RECIPES designed for days when you want one dish to do all the work for you. Expect rich, mouthwatering layers that are just begging to be on your dinner table.
Immediate eBook download. No physical book available.
Includes ad-free recipes like:
∙ Breakfast Casserole
∙ Cheeseburger Casserole
∙ Four Cheese Ravioli Casserole
∙ Chicken Pot Pie Casserole
∙ Sweet Potato Casserole
...and much more!
Combine and Transfer
Layer the cooked spaghetti at the bottom of a lightly greased 9×13-inch casserole dish, making sure to fully cover the bottom. I love using my ceramic casserole dish because it heats evenly, leaving you no uneven hot spots.
Add the cooked chicken to the sauce and mix well until every strand is evenly coated, then transfer everything to the dish and spread it evenly over the spaghetti. Sprinkle the remaining cheese across the top.
Bake Until Golden
Bake in a preheated oven at 375°F (190°C) for 25 minutes, until the casserole is bubbly and the cheese on top is golden. Let it rest for 10 minutes before serving, then garnish with fresh parsley.
Serve warm and enjoy!
Cheesy Chicken Spaghetti Casserole
Add Preferred SourceIngredients
- 2 boneless skinless chicken breasts cut into cubes
- 8 ounces spaghetti
- 2 tablespoons olive oil
- 2 tablespoons butter
- 1 small onion diced
- 1 cup sliced mushrooms
- 3 garlic cloves minced
- 2 tablespoons all-purpose flour
- 1 1/2 cups chicken broth
- 1 cup Rotel diced tomatoes with green chilies
- Salt to taste
- Black pepper to taste
- 1 cup heavy cream
- 1 cup shredded cheddar cheese
- 1 cup shredded mozzarella cheese
- Fresh parsley for garnish
Instructions
- Brown the chicken cubes in olive oil over medium heat until golden and fully cooked (7–10 minutes). Set aside.2 boneless skinless chicken breasts, 2 tablespoons olive oil
- Cook the spaghetti in salted water until al dente. Drain and set aside.8 ounces spaghetti
- In the same pan, melt the butter and sauté the onion and garlic until soft. Add the mushrooms and cook for 2 more minutes. Stir in the flour and cook for 1–2 minutes until lightly golden.2 tablespoons butter, 1 small onion, 1 cup sliced mushrooms, 3 garlic cloves, 2 tablespoons all-purpose flour
- Gradually whisk in the chicken broth, rotel tomatoes and then add the cream. Cook until the sauce thickens. Season with salt and pepper, then stir in half of the cheese until smooth.1 1/2 cups chicken broth, 1 cup Rotel diced tomatoes with green chilies, Salt, Black pepper, 1 cup heavy cream, 1 cup shredded cheddar cheese, 1 cup shredded mozzarella cheese
- Add the chicken to the sauce and mix well.
- Place the cooked spaghetti pasta in a greased 9×13-inch baking dish. Pour the chicken sauce and sprinkle with the remaining cheese.
- Bake at 375°F (190°C) for 25 minutes, until bubbly and golden. Let rest for 10 minutes before serving.
- Garnish with fresh parsley.Fresh parsley
Notes
Nutrition
SERIOUSLY GOOD
CASSEROLES
37 EASY RECIPES designed for days when you want one dish to do all the work for you. Expect rich, mouthwatering layers that are just begging to be on your dinner table.
Immediate eBook download. No physical book available.
Includes ad-free recipes like:
∙ Breakfast Casserole
∙ Cheeseburger Casserole
∙ Four Cheese Ravioli Casserole
∙ Chicken Pot Pie Casserole
∙ Sweet Potato Casserole
...and much more!
How to Store Leftovers
Let the casserole cool completely before storing. Transfer leftovers to an airtight container or cover the baking dish tightly with foil and refrigerate for 3 to 4 days.
To reheat, add a small splash of chicken broth, milk, or cream over the top before microwaving in 60-second intervals or warming in a 350°F oven for about 15 minutes to bring the sauce back to life.
To freeze, portion the cooled casserole into individual servings and store in freezer-safe containers for 2 to 3 months. Thaw overnight in the fridge before reheating and adding any garnishes.
What to Serve With Cheesy Chicken Spaghetti Casserole
A simple green salad with a bright vinaigrette is the most natural pairing here because the acidity cuts right through the richness of the creamy sauce. Garlic bread or a warm crusty loaf on the side is practically non-negotiable for scooping up every last bit of that cheesy Rotel sauce.
Roasted broccoli, steamed green beans, or a quick sautéed zucchini all work really well as vegetable sides if you want something more filling alongside. The casserole is rich enough to be the star, so keep the sides simple and you’ll have a dinner that comes together without any stress.
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