Chicken Spaghetti Squash Casserole

This chicken spaghetti squash casserole is one of those easy dinners I keep coming back to when I want something comforting but still light. It’s creamy, cheesy, and packed with flavor, made with tender spaghetti squash, juicy shredded chicken, and melty mozzarella all baked together in a rich, savory sauce.

This Chicken Spaghetti Squash Casserole Tastes Like a Classic Pasta Bake (But It’s Low Carb)

I made this chicken spaghetti squash casserole on one of those busy evenings when I needed something easy but still comforting. I wasn’t expecting much, but it turned out so creamy, cheesy, and satisfying that everyone went back for seconds. Since then, it’s been on repeat, especially when I want a cozy dinner that doesn’t feel too heavy.

And now I understand why:

• Feels like a classic pasta bake – It has everything you love about a creamy casserole, with shredded chicken, melty mozzarella, and a rich sauce, but made with spaghetti squash instead of pasta for a lighter, low carb twist.
• Creamy, cheesy, and full of flavor – The sauce brings everything together, the cheese melts perfectly, and the chicken stays juicy in every bite.
• Easy to make on busy days – This is one of those easy chicken spaghetti squash casserole recipes you can throw together without overthinking it.
• Lighter but still satisfying – Using spaghetti squash keeps it gluten-free and lower in carbs, but it still feels like comfort food.
• Great for meal prep – I usually make a bigger batch because it reheats really well and tastes just as good the next day.
• Works for the whole family – It makes a generous portion, and even picky eaters tend to love it.

In our home, casseroles are a must-have at our holiday dinner parties, and just like my green bean casserole, Philly cheesesteak casserole, and creamy chicken divan casserole, this quick Chicken Spaghetti Squash Casserole is always a favorite. It’s simple to make and brings everyone together with its creamy, cheesy goodness. This casserole always feels like home, whether for a big celebration or a casual dinner.

Simple Ingredients, Big Flavor (With Easy Swaps)

This chicken spaghetti squash casserole comes together with simple, everyday ingredients, but the combination is what makes it so creamy, comforting, and easy to love. I’ve also added a few swaps in case you want to adjust based on what you have.

• Cooked chicken – I usually grab a shredded rotisserie chicken when I want to keep things quick and easy. It adds great flavor and stays juicy. Leftover chicken breast or thighs work just as well, so this is a great way to use what you already have.
• Spaghetti squash – This is what makes this a lighter chicken spaghetti squash casserole recipe. Once roasted and shredded, it has that tender, slightly stringy texture that works really well in place of pasta. If you don’t have one, you can use zucchini noodles, just keep in mind they release more moisture.
• Cream cheese – This is what makes the sauce extra creamy and smooth. I like using full-fat for the best texture, but a lighter version works too.
• Sour cream – Adds a subtle tang that balances all the richness. If you don’t have sour cream, plain Greek yogurt is a really good substitute and adds a bit of extra protein.
• Mozzarella and Parmesan cheese – Mozzarella gives you that melty, cheesy texture, while Parmesan adds more flavor. I like using freshly grated cheese when I can because it melts better, but pre-shredded works fine for convenience.
• Spinach – I like adding a handful of spinach for a quick veggie boost. Fresh or frozen both work. If you’re using frozen, just make sure to squeeze out the extra water so the casserole doesn’t turn out watery.
• Garlic – Fresh garlic adds the best flavor here, but garlic powder works if that’s what you have on hand.
• Olive oil – Used for roasting the spaghetti squash and adding a bit of richness to the dish. Any neutral oil works if needed.
• Salt and pepper – Simple, but important. They bring everything together and really help balance the creamy sauce.

How To Make Chicken Spaghetti Squash Casserole 

Making this casserole is super easy! Just follow a few simple steps, and you’ll have a creamy, delicious dish ready to enjoy in no time. Here is everything you need to do:

Start with the Spaghetti Squash

I like to get the squash in the oven first so everything else comes together faster.

Preheat your oven to 400°F (200°C). Slice the spaghetti squash in half lengthwise and scoop out the seeds. You can discard them or save them to roast later.

Brush the inside with olive oil, then season with salt and pepper. Place the halves cut side down on a lined baking sheet and roast for about 40–50 minutes, until the squash is tender and easily shreds into strands with a fork.

If your squash is smaller or larger, the timing might vary a bit. You’ll know it’s ready when the strands pull apart easily.

Season the Squash. Brush the inside of each half with olive oil to help it roast evenly and add flavor. Sprinkle with salt and pepper to taste. This step enhances the natural sweetness of the squash.

Roast the Squash. Place the squash halves cut side down on a baking sheet lined with parchment paper for easy cleanup. Roast in the oven for 40-50 minutes or until the flesh is tender.

You can check by poking the squash with a fork; it should easily shred into spaghetti-like strands.

Tip: If your squash is particularly large or small, you may need to adjust the roasting time slightly. The squash is done when soft, and the fork easily pulls the strands apart.

Make the Creamy Chicken Filling

While the squash is roasting, start on the filling.

In a large bowl, mix together the cream cheese, mozzarella, Parmesan, sour cream, and garlic until smooth. I find it helps if the cream cheese is at room temperature so everything blends easily.

Once the mixture is creamy, stir in the shredded chicken and spinach. If you’re using frozen spinach, make sure to squeeze out as much liquid as possible so the casserole doesn’t turn watery.

Tip: If you prefer more vegetables, you can add other ingredients like diced bell peppers or mushrooms to the mix.

Shred the Spaghetti Squash

Cool the Squash. Once the squash is done roasting, remove it from the oven and let it cool for about 5-10 minutes so you can handle it safely.

Shred the Squash. Use a fork to scrape the squash’s flesh into spaghetti-like strands gently. Hold the squash half steady while you scrape to avoid it slipping.

Tip: If you want a less stringy texture, you can use a spoon to scoop out the squash, but shredding with a fork gives it that pasta-like feel that makes it a great substitute for noodles.

Assemble and Bake the Casserole

Mix the Shredded Squash into the Casserole. Add the shredded squash to the cheese, chicken, and spinach mixture. Stir it all together until everything is evenly combined.

Transfer to Baking Dish. Grease a baking dish with a bit of olive oil or cooking spray. Transfer the mixture to the dish, spreading it evenly to ensure even baking.

Bake the Casserole. Place the casserole in the oven and bake for 20-25 minutes or until the top is golden brown and bubbly. The cheese should melt and form a nice, crisp layer on top.

Tip: If you want a more golden top, broil the casserole for 2-3 minutes, but watch carefully to prevent burning.

Let It Rest, Then Serve

Once it’s out of the oven, let the casserole sit for a few minutes before serving. This helps it set and makes it easier to scoop.

My Pro Tips for the Best Chicken Spaghetti Squash Casserole

• Pick a good spaghetti squash – I always look for one that feels firm and heavy for its size, with no soft spots. A good squash roasts more evenly and gives you those perfect tender strands.
• Roast it cut-side down – This is the easiest way to get the best texture. Roasting the spaghetti squash cut-side down helps it cook through evenly while keeping it tender, not dry.
• Make it easier to cut – If the squash feels too hard to slice, I like to microwave it whole for about 3–5 minutes first. It softens just enough to make cutting much easier (and safer).
• Don’t over-shred it – Once it’s roasted, let it cool slightly, then use a fork to gently pull it into strands. This keeps the texture light and prevents it from turning mushy.
• Watch the moisture – This is probably the most important tip. If the squash looks watery after shredding, I usually pat it dry with paper towels before mixing it in. This helps keep the casserole creamy, not soggy.

Chicken Spaghetti Squash Casserole FAQs

More of My Favorite Casserole Recipes

• Green Bean Casserole
• Chicken Bacon Ranch Casserole
• Squash Casserole