Spaghetti, tender chicken, and a homemade white sauce under melted colby jack — one nine by thirteen, twenty minutes in the oven, and leftovers people actually want.
Three things that keep it creamy, not mushy
The crock of this recipe is the white sauce, and these are the three places it goes right or wrong.
- Cook the pasta al dente: It bakes another twenty minutes, so noodles boiled soft going in come out mushy.
- Keep stirring the sauce: The half and half and parmesan go in while you whisk. Walking away makes it grainy.
- Use cooked chicken: Three cups of shredded rotisserie or Instant Pot chicken and the hard part is done.
When I know we are going to have a busy week, casseroles are going to be on the menu and this chicken spaghetti is always a go-to because my entire family loves it.
This is the pan I grab when the week looks rough. It makes a nine by thirteen full of creamy, cheesy pasta, and the leftovers are the kind people actually go back for.
One casserole on Monday quietly becomes lunch on Tuesday.

Cheesy Chicken Spaghetti
We are big fans of chicken in our household, and we love leftovers. I know not every family loves eating leftovers, and I should consider myself lucky!
When I think of a casserole that will provide lots of leftovers, cheesy chicken spaghetti casserole comes to mind. You’ll love this chicken pasta bake, and be much like me – when I’m planning it I think of four things: spaghetti noodles, cheesy inside/topping, white sauce and tender chicken.
Great news: if those are the four things that you also think about, you are in luck because this chicken spaghetti casserole has all four of those things and more!
Here is how I whip up my best chicken spaghetti recipe:
Everything You Need
- 1/4 cup butter
- 1 small onion, diced
- 3 garlic cloves, minced
- 3 T all purpose flour
- 2 cups chicken broth
- 1 cup half and half
- 3/4 cups parmesan cheese, shredded
- 3 cups cooked, shredded chicken
- 8 oz. spaghetti
- 1 cup shredded colby jack cheese
How to Make Chicken Spaghetti
- Preheat oven to 350 degrees
- Cook spaghetti al dente
- While spaghetti is cooking melt butter over medium to low heat
- Add onions and garlic, cook 3-5 minutes while stirring
- Stir in the flour and mix well for a minute
- Stir in the chicken broth, allowing mixture to come to a boil
- Whisk in the half and half while stirring constantly
- Stir in parmesan cheese, stirring constantly, until the mixture is a little thickened, and remove from heat
- Add chicken and pasta to mixture, combining with the white sauce
- Pour chicken, noodle and sauce mixture into a greased 9x 13 baking dish
- Top casserole with colby jack cheese
- Cover casserole with foil and bake 20 minutes until cheese is melted and casserole is warmed through
- Enjoy!
The White Sauce Is the Whole Recipe
All the other parts here are assembly, but the sauce is where the flavor comes from. Butter, onion and garlic go in first, then three to five minutes of cooking before the flour goes in.
Once the chicken broth comes to a boil, the butter and flour thicken it. Half and half and parmesan finish it into a white sauce that clings to the spaghetti instead of pooling in the dish.
The only rule is to keep stirring. The half and half and the parmesan both go in while you are whisking, and walking away is how a smooth sauce turns grainy.
What I Have Learned Making This
Cook the spaghetti al dente and not a minute more. The casserole spends another twenty minutes in the oven, and noodles boiled soft going in come out mushy.
Use chicken you already cooked. Three cups of cooked, shredded chicken is the whole requirement, so a rotisserie bird or a batch of Instant Pot chicken made earlier in the week both work.
Leave the foil on during the bake. The casserole only needs to heat through and melt the cheese, and the foil keeps the top from drying out in those twenty minutes.
What is chicken spaghetti?
Chicken spaghetti is like a regular spaghetti, but, switch the ground beef for chicken and the red sauce out for white sauce.
Chicken spaghetti is also usually topped with colby jack cheese, or cheddar cheese and then baked.
What goes with chicken spaghetti?
If you’re wondering what sides go good with chicken spaghetti, I usually serve chicken spaghetti with garlic bread and some veggies. This cheap and east chicken spaghetti is pretty good on its own, too!
Can I use cheddar instead of colby jack?
Yes. Chicken spaghetti is usually topped with colby jack or cheddar, so use whichever one your family likes or whatever is already in the drawer.
Can I use rotisserie chicken?
Rotisserie chicken is an easy way to get the three cups of cooked, shredded chicken this calls for. I usually make a batch of shredded chicken in the Instant Pot early in the week and pull from that.
How long will chicken spaghetti stay good in the refrigerator?
Chicken spaghetti will last in the refrigerator for four days. Please take into account when you prepare the chicken because it will be four days from this date.
For example, I usually bake and shred 6-7 chicken breasts in the Instant Pot using this shredded chicken thighs instant pot recipe. So, if I cook the chicken things and a Wednesday, but don’t make the chicken spaghetti casserole until Wednesday, I would consider the cheesy chicken spaghetti recipe to be good for three more days, through Sunday.
This is not a fancy dinner and it is not trying to be. It is a warm pan of cheesy pasta that feeds the whole house and hands you tomorrow’s lunch for free.

Chicken Spaghetti
Ingredients
- 1/4 cup butter
- 1 onion
- 3 garlic cloves
- 3 T all-purpose flour
- 2 cups chicken broth
- 1 cup half and half
- 3/4 cup parmesan cheese
- 3 cups cooked & shredded chicken
- 8 oz spaghetti noodles
- 1 cup shredded colby jack cheese

