Chicken Spaghetti Squash Casserole

If you’re craving a rich, cheesy casserole but want to keep things lighter and low-carb, this Chicken Spaghetti Squash Casserole is the perfect solution. It delivers all the creamy, comforting flavors of a classic chicken pasta bake—without the pasta.
Tender strands of roasted spaghetti squash replace traditional noodles, while shredded chicken, savory vegetables, and a creamy, cheesy sauce come together for a satisfying, wholesome meal. It’s ideal for weeknight dinners, meal prep, or when you want comfort food without the heaviness.

Why You’ll Love This Recipe

• Low-carb and keto-friendly comfort food
• Creamy, cheesy, and packed with flavor
• Great way to use leftover or rotisserie chicken
• Loaded with veggies for a balanced meal
• Perfect for meal prep and reheats beautifully

Ingredients

• 1 medium spaghetti squash – A low-carb alternative to pasta with a mild, slightly sweet flavor
• 4 cups cooked shredded chicken – Adds protein and heartiness
• 5 tbsp butter – Creates a rich base for sautéing
• 1 cup diced celery – Adds crunch and depth
• 1 medium onion, diced – Builds savory flavor
• 1 poblano pepper, diced – Adds mild heat and smokiness
• 1 bell pepper, diced – Brings sweetness and color
• 5 cloves garlic, minced – Adds bold aromatic flavor
• ⅓ cup chicken stock – Helps create a flavorful sauce
• 1 (10 oz) can diced chiles and tomatoes, drained – Adds tang and mild spice
• 1 cup heavy cream – Creates a rich, creamy texture
• 5 oz cream cheese – Adds thickness and tangy richness
• 1 tsp cumin – Adds warm, earthy flavor
• ½ tsp garlic powder – Enhances savory notes
• ¼ tsp pepper – Adds subtle heat
• 1½ cups shredded Colby Jack cheese – Melty, cheesy topping and filling

How to Make Chicken Spaghetti Squash Casserole

1. Prepare and Roast the Squash

Preheat your oven to 400°F (200°C).
Microwave the whole spaghetti squash for 4–5 minutes to soften it slightly (this makes cutting much easier).

Carefully trim the ends, then slice it lengthwise. Scoop out the seeds.
Drizzle with olive oil, sprinkle with salt, and place cut-side down on a lined baking sheet.
Roast for about 30 minutes, or until tender.

2. Cook the Vegetables

While the squash roasts, melt butter in a large skillet over medium-high heat.
Add onion, celery, poblano, and bell pepper. Cook for about 7 minutes until softened.
Add garlic and cook for another 1–2 minutes until fragrant.

3. Build the Sauce

Pour in chicken stock along with the drained tomatoes and chiles.
Let it cook until the liquid reduces by about half.

Add heavy cream and simmer until thickened and creamy. Remove from heat.

4. Mix the Filling

Transfer the veggie mixture to a large bowl.
Add cream cheese, cumin, garlic powder, and pepper. Stir until smooth and well combined.

5. Prepare the Squash

Remove the squash from the oven and flip it over.
Use a fork to scrape out the spaghetti-like strands.

If the squash is watery, pat it dry with paper towels—this step is key to avoiding a soggy casserole.

6. Combine Everything

Lower oven temperature to 350°F (175°C).
Add the squash strands to the bowl with the sauce.

Gently stir in shredded chicken and ½ cup of the cheese until evenly combined.

7. Assemble and Bake

Transfer the mixture into a greased casserole dish (9×13 works well).
Top with the remaining cheese.

Bake for 20 minutes, or until the cheese is melted, bubbly, and lightly golden.

8. Rest and Serve

Let the casserole sit for about 10 minutes before serving. This helps it set and makes it easier to slice.

Tips for Success

• Microwave the squash first to make cutting easier and safer
• Remove excess moisture from squash to prevent a watery casserole
• Use rotisserie chicken for a quick shortcut
• Don’t overcook the squash—it should be tender but not mushy
• Let the casserole rest before serving for better texture

Equipment Needed

• Baking sheet
• Large skillet
• Mixing bowl
• Casserole dish (9×13)
• Knife and cutting board
• Fork (for shredding squash)

Recipe Variations

• Spicy Version: Add jalapeños or red pepper flakes
• Extra Cheesy: Mix in cheddar or mozzarella for more gooey texture
• Dairy-Free Option: Use coconut cream and dairy-free cheese alternatives
• Turkey Version: Swap chicken for ground turkey
• Vegetarian Option: Replace chicken with mushrooms or roasted cauliflower

Serving Suggestions

• Serve with a simple green salad for a balanced meal
• Add sliced avocado for extra creaminess
• Pair with roasted vegetables for a hearty dinner
• Garnish with fresh herbs like parsley or cilantro

FAQs

Can I make this casserole ahead of time?
Yes! Assemble it ahead and refrigerate, then bake when ready.

How do I store leftovers?
Store in an airtight container in the fridge for up to 4 days.

Can I freeze this casserole?
Yes, freeze after baking. Thaw overnight and reheat in the oven.

Why is my casserole watery?
This usually happens if the spaghetti squash isn’t drained properly. Be sure to remove excess moisture.

Can I use pre-cooked chicken?
Absolutely! Rotisserie chicken works perfectly and saves time.

Is this keto-friendly?
Yes, it’s low in carbs and fits well into a keto lifestyle.

Final Thoughts

This Chicken Spaghetti Squash Casserole is the ultimate combination of comfort and nutrition. It’s creamy, cheesy, and satisfying while still being low-carb and packed with wholesome ingredients.
Whether you’re meal prepping or feeding your family, this dish delivers big flavor with minimal effort. Give it a try and enjoy a lighter take on classic comfort food!

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