Pour the spaghetti squash mixture into a greased 9×13 inch baking dish Recipe

If you’re on the hunt for a comforting, cheesy dish that also sneaks in some wholesome goodness, this spaghetti squash au gratin will quickly become a new favorite. The magic begins when you pour the spaghetti squash mixture into a greased 9×13 inch baking dish, layering strands of tender squash with a rich, velvety cheese sauce that’s perfectly seasoned with nutmeg and garlic. It’s a colorful, textured feast that bakes up golden with a crispy breadcrumb topping, offering all the satisfaction of a classic gratin but with the lightness of vegetable-forward cooking.

Ingredients You’ll Need

Everything in this recipe is simple, straightforward, and each ingredient plays a vital role in building the dish’s rich flavor and inviting texture. From the creamy Gruyere to the nutty Parmesan and that lightly sweet spaghetti squash base, every element counts.

• Spaghetti squash: The star of the show, providing natural “spaghetti” strands that are light and nutrient-rich.
• Unsalted butter: Divided to enrich both the squash and the creamy sauce, giving a smooth mouthfeel.
• Yellow onion: Finely chopped for a sweet, aromatic base that melts beautifully into the sauce.
• Garlic: Minced for a fragrant punch that complements the cheese perfectly.
• All-purpose flour: The thickening agent for the luscious sauce, helping it cling to every squash strand.
• Whole milk: Creates a creamy, indulgent sauce without heaviness.
• Salt and black pepper: Essential for balanced seasoning throughout the dish.
• Nutmeg: Adds a subtle warmth, elevating the sauce with its gentle spice.
• Gruyere cheese: Melted into the sauce for that signature nutty, slightly sweet flavor.
• Sharp cheddar cheese: Adds robust sharpness and depth to the creamy base.
• Parmesan cheese: Sprinkled in and on top for umami and a delightful salty finish.
• Panko breadcrumbs: For that irresistible golden crust that adds a nice crunch.
• Fresh parsley: Optional, but freshens and brightens the dish right at the end.

How to Make Pour the spaghetti squash mixture into a greased 9×13 inch baking dish

Step 1: Roast the Spaghetti Squash

Begin by cutting your spaghetti squash in half lengthwise and scooping out the seeds. A quick drizzle of melted butter on the cut sides, plus a generous sprinkle of salt and pepper, ensures the flavor starts right at the base. Place the halves cut-side down on a baking sheet and roast at 400°F until the flesh is tender and easily pierced by a fork – about 45 to 60 minutes. This slow roasting enhances the natural sweetness and softens the squash to just the right texture for shredding.

Step 2: Shred the Squash

Once your squash is cool enough to handle, gently rake a fork across the flesh to separate it into spaghetti-like strands. This unique texture is what makes this dish so fun and satisfying. Now the stage is set to build layers of creamy goodness!

Step 3: Make the Creamy Cheese Sauce

In a saucepan, melt the remaining butter and sauté the finely chopped onion over medium heat until translucent and tender. Adding the garlic for just one minute more releases wonderful aroma without overwhelming. Stir in the flour to form a roux – this cooks out the raw taste and thickens the sauce beautifully. Gradually whisk in whole milk, stirring continuously until the sauce is smooth, then simmer gently until it thickens while you season with salt, pepper, and a pinch of nutmeg. The finishing cheesy blend of Gruyere, cheddar, and Parmesan transforms this sauce into a velvety, flavorful hug for the squash strands.

Step 4: Combine and Bake

Now comes the moment where you truly come together with the magic. Pour the spaghetti squash mixture into a greased 9×13 inch baking dish, allowing every tender strand to soak in the luscious cheese sauce. Top with a mixture of remaining cheeses and crunchy panko breadcrumbs for that perfect gratin finish. Pop it in the oven for about 20-25 minutes until golden brown and bubbly. The bubbling cheese and crispy topping make this dish impossible to resist!

How to Serve Pour the spaghetti squash mixture into a greased 9×13 inch baking dish

Garnishes

Fresh parsley sprinkled atop just before serving adds a bright, herbal counterpoint to all that rich, cheesy indulgence. If you want a little extra flair, a dusting of freshly cracked black pepper completes the seasonings beautifully and awakens the palate.

Side Dishes

This dish shines as a hearty vegetarian main but also pairs splendidly alongside a crisp green salad with a lemony vinaigrette or simple roasted vegetables for a well-rounded and satisfying meal. The creamy au gratin texture contrasts wonderfully with fresh, crunchy sides that refresh the palate.

Creative Ways to Present

Serving this spaghetti squash au gratin in individual ramekins or mini cast iron skillets creates a charming presentation for dinner parties or cozy family meals. You could also swirl in some cooked bacon or caramelized mushrooms before you pour the spaghetti squash mixture into a greased 9×13 inch baking dish for an added layer of flavor and texture.

Make Ahead and Storage

Storing Leftovers

This dish keeps beautifully in the refrigerator for up to 4 days. Simply cover your leftovers tightly with foil or plastic wrap to maintain moisture, then reheat gently when you’re ready to enjoy again.

Freezing

Although best enjoyed fresh, you can freeze the unbaked casserole by assembling everything and covering it tightly with foil and plastic wrap. When ready, thaw overnight in the refrigerator and bake as usual. Keep in mind the breadcrumb topping might lose some crispness when frozen.

Reheating

To reheat, cover the baking dish loosely with foil and pop it into a 350°F oven until warmed through, about 15-20 minutes. Removing the foil towards the end brings back some of that lovely golden crust.

FAQs

Can I use low-fat milk instead of whole milk?

Yes, you can substitute low-fat milk, but the sauce will be less creamy and rich. For the best silky sauce texture, whole milk or a mix with a bit of cream is recommended.

What if I don’t have Gruyere cheese?

Gruyere adds a distinctive nutty flavor, but you can swap it with Swiss cheese or even mozzarella for melting, though the flavor will be milder.

Can I prepare this dish ahead and refrigerate before baking?

Absolutely! You can assemble the au gratin, then cover and refrigerate for up to 24 hours before baking. Just add a few extra minutes to the baking time if baking straight from the fridge.

Is spaghetti squash difficult to cook?

Not at all! Roasting is the simplest way, and it enhances the natural sweetness while softening the flesh perfectly for shredding. Cutting and roasting take about an hour total but mostly hands-off time.

Can I make this recipe dairy-free?

For a dairy-free version, you would need to use plant-based butter and milk alternatives, plus vegan cheese substitutes. Keep in mind the flavor and creaminess will differ, but it’s definitely doable for a lighter spin.

Final Thoughts

This spaghetti squash au gratin is one of those dishes that feel like a warm hug on a plate—comforting, creamy, and packed with flavor and texture. When you pour the spaghetti squash mixture into a greased 9×13 inch baking dish and bake it to golden perfection, you’re creating something truly special that’s perfect for weeknight dinners or special gatherings. I can’t wait for you to try this recipe and share the joy of veggie-forward comfort food with your loved ones!

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