Name: Cheesy Spaghetti Squash Casserole Recipe
Prep time: 15 min
Cook time: 40 min
Total time: 55 min
Cuisine: American
Ingredients: 1 (3 pounds) raw spaghetti squash – or 2 ½ cups cooked spaghetti squash (450 grams); 1 large egg; ½ cup sour cream; 1 tablespoon fresh garlic – minced; 1 teaspoon Diamond Crystal kosher salt (or ½ teaspoon other kosher salt); ¼ teaspoon black pepper; ½ teaspoon dried thyme; 1 cup sharp cheddar cheese – shredded; Olive oil cooking spray

Jump to Recipe· 3.9 from 11 reviews

If you’re looking for a dish that’s hearty, comforting, and packed with flavor while sneaking in a healthy veggie, then this Cheesy Spaghetti Squash Casserole Recipe is your new best friend in the kitchen. Combining tender strands of spaghetti squash with a rich blend of sharp cheddar, creamy sour cream, and warm seasonings, this casserole bakes to golden perfection and delivers a cheesy, savory delight that everyone will adore. It’s an easy-to-make, crowd-pleasing meal that feels indulgent but is surprisingly light, making it perfect anytime you crave cheesy goodness with a nutritious twist.

Ingredients You’ll Need

A clear glass bowl is filled with a mixture that has two layers: the bottom layer is pale yellow with a creamy texture, and the top layer is a thick heap of shredded light yellow cheese. A woman's hand is holding the bowl steady on the right side, while another woman's hand uses a bright yellow spatula to stir the cheese, causing some cheese shreds to blur with motion. The bowl is placed on a white marbled surface. photo taken with an iphone --ar 4:5 --v 7

Gathering a handful of simple, fresh ingredients is all it takes to make this casserole shine. Each ingredient has its moment—whether it’s the tender spaghetti squash providing texture, the sharp cheddar adding depth, or the herbs bringing aromatic balance.

Olive oil cooking spray: Helps prevent sticking and ensures the casserole’s edges brown beautifully.
1 (3 pounds) raw spaghetti squash: This forms the base of the dish with its mild, slightly sweet flavor and spaghetti-like texture.
1 large egg: Binds all the ingredients together for a perfect casserole consistency.
½ cup sour cream: Adds creamy moisture and a subtle tang to enrich the flavor.
1 teaspoon Diamond Crystal kosher salt: Seasoning is crucial, and kosher salt distributes flavor without overpowering.
¼ teaspoon black pepper: Gives a gentle, warming kick throughout the casserole.
½ teaspoon dried thyme: Brings a fragrant herbal note that complements the cheese beautifully.
1 tablespoon fresh garlic (minced): Adds vibrant aroma and zing, instantly boosting the savory vibe.
1 cup sharp cheddar cheese (shredded): The star ingredient providing cheesy richness and a satisfying melt.

How to Make Cheesy Spaghetti Squash Casserole Recipe

Step 1: Prep the Spaghetti Squash

Start by piercing the whole spaghetti squash several times with a sharp knife. Pop it into the microwave for 6 minutes on one side, then flip it and microwave for another 6. This quick cooking softens it perfectly. Let it rest for 5 minutes to finish steaming, then slice it open, scoop out the seeds, and rake a fork across the flesh to create those iconic spaghetti-like strands. This texture is what makes the Cheesy Spaghetti Squash Casserole Recipe so impressive and fun to eat.

Step 2: Mix the Filling

In a large mixing bowl, whisk the egg lightly before stirring in the sour cream, kosher salt, black pepper, thyme, and minced garlic until smooth and fragrant. Incorporate the cooked squash strands and shredded cheddar cheese, tossing gently but thoroughly to make sure every bit is coated in creamy, cheesy goodness. This step melds all the flavors and prepares the irresistible filling for baking.

Step 3: Bake to Perfection

Spray a 1.5-quart baking dish with olive oil cooking spray to avoid sticking and promote browning. Transfer your squash and cheese mixture into the dish and spread evenly. Slide it into a preheated 400°F oven and bake for about 40 minutes until it turns a beautiful golden brown on top, bubbling with savory aromas that will fill your kitchen with warmth and welcome. Let the casserole rest for 10 minutes after baking—it will firm up slightly, making it easier to slice and serve.

How to Serve Cheesy Spaghetti Squash Casserole Recipe

A large white pot filled almost to the top with a thick, yellow, cheesy baked dish with a slightly browned edge. A spoon lifts a big scoop of the soft, stringy cheese mixture, showing its gooey texture with strands stretching from the pot. The pot sits on a white marbled surface with a striped cloth in the background. The handle of the pot is visible and the light shows the creamy, dense texture of the cheese dish inside. photo taken with an iphone --ar 4:5 --v 7

Garnishes

While this casserole is delicious on its own, a sprinkle of fresh chopped parsley or chives can add a pop of color and a hint of freshness that lightly cuts through the richness. For a little extra zing, a dusting of smoked paprika or a drizzle of hot sauce on top can raise the cozy flavors to exciting new levels.

Side Dishes

This casserole pairs wonderfully with vibrant green salads dressed in tangy vinaigrette or roasted vegetables like asparagus or Brussels sprouts, which complement the cheesy texture without overpowering it. For a heartier meal, roasted chicken or grilled sausages make perfect companions that round out the plate with protein and robust flavor.

Creative Ways to Present

Serving this casserole in individual ramekins or mini cast iron skillets adds a charming touch for guests or family dinners. Alternatively, cut it into neat squares and arrange them on a platter topped with fresh herbs for a delightful potluck or buffet offering. This approachable presentation makes the Cheesy Spaghetti Squash Casserole Recipe feel just a little extra special and festive.

Make Ahead and Storage

Storing Leftovers

Any leftovers should be cooled completely before being transferred to an airtight container. Stored in the refrigerator, the casserole will keep well for up to 4 days without losing its cheesy charm or the texture of the spaghetti squash strands.

Freezing

This casserole freezes beautifully if you want to prep ahead. Wrap tightly with plastic wrap and aluminum foil or place in a freezer-safe container. It will keep in the freezer for up to 3 months. When ready, thaw overnight in the refrigerator before reheating for best results.

Reheating

Reheat leftovers gently in the oven at 350°F until warmed through, about 15-20 minutes. You can also microwave individual servings, but the oven method helps preserve the casserole’s texture and prevents it from becoming soggy while keeping the cheese melty and delightful.

FAQs

Can I substitute the sour cream with something else?

Absolutely! Greek yogurt or crème fraîche are great alternatives that still provide creaminess and a bit of tang without compromising the texture.

Is spaghetti squash low-carb?

Yes, compared to traditional pasta, spaghetti squash is much lower in carbohydrates and a fantastic option if you’re looking to reduce carbs without giving up that noodle-like feel.

Can I make this recipe vegan?

For a vegan version, swap the egg with a flax or chia egg, use a vegan sour cream substitute, and replace cheddar with a plant-based cheese. Keep in mind the texture and flavor will vary slightly but remain tasty!

What if I don’t have a microwave?

No worries! You can bake the whole spaghetti squash at 400°F for about 40-50 minutes or until tender. Just be sure to let it cool before scooping out the strands.

How can I add protein to this casserole?

Mix in cooked ground turkey, shredded chicken, or cooked beans before baking to make it a heartier, protein-packed meal everyone will love.

Final Thoughts

This Cheesy Spaghetti Squash Casserole Recipe is a wonderful way to enjoy comforting, cheesy flavors while embracing the natural goodness of vegetables. It’s simple to make, incredibly satisfying, and a true crowd-pleaser that will quickly become a staple in your recipe collection. I can’t wait for you to try it and experience just how delightful healthy comfort food can be!