Spaghetti Squash Au Gratin Recipe

Spaghetti Squash Au Gratin is a comforting and healthy twist on a classic dish. This creamy, cheesy bake combines tender roasted spaghetti squash with rich Gruyere and cheddar cheeses for a satisfying meal that’s perfect for any occasion.

Ingredients

• 1 large spaghetti squash (about 3-4 pounds)
• 4 tablespoons unsalted butter, divided
• 1 medium yellow onion, finely chopped
• 2 cloves garlic, minced
• 4 tablespoons all-purpose flour
• 3 cups whole milk
• 1/2 teaspoon salt, plus more to taste
• 1/4 teaspoon black pepper, plus more to taste
• 1/4 teaspoon nutmeg
• 1 cup grated Gruyere cheese, divided
• 1 cup grated sharp cheddar cheese, divided
• 1/2 cup grated Parmesan cheese, divided
• 1/4 cup panko breadcrumbs
• 2 tablespoons chopped fresh parsley, for garnish (optional)

Instructions

1. Step 1: Preheat the oven to 400°F (200°C). Cut the spaghetti squash in half lengthwise and scoop out the seeds and stringy bits.
2. Step 2: Drizzle the cut sides of the squash with 2 tablespoons of melted butter and sprinkle generously with salt and pepper.
3. Step 3: Place the squash halves cut-side down on a baking sheet lined with parchment paper. Roast for 45-60 minutes until the flesh is tender and easily pierced with a fork.
4. Step 4: Once cool enough to handle, use a fork to shred the flesh into spaghetti-like strands and set aside.
5. Step 5: In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter. Add the chopped onion and cook until softened and translucent, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.
6. Step 6: Sprinkle the flour over the onion and garlic mixture. Cook, stirring constantly, for 1-2 minutes to make a roux.
7. Step 7: Gradually whisk in the milk, a little at a time, ensuring no lumps form. Continue whisking until the sauce is smooth.
8. Step 8: Bring the sauce to a simmer over medium heat, stirring constantly. Reduce heat to low and simmer for 5-7 minutes until the sauce thickens slightly.
9. Step 9: Stir in salt, pepper, and nutmeg. Taste and adjust seasonings as needed.
10. Step 10: Remove the saucepan from heat. Stir in 3/4 cup of Gruyere, 3/4 cup of cheddar, and 1/4 cup of Parmesan cheese until melted and the sauce is creamy.
11. Step 11: Add the shredded spaghetti squash to the cheese sauce and gently combine.
12. Step 12: Pour the mixture into a greased 9×13 inch baking dish.
13. Step 13: In a small bowl, combine the remaining 1/4 cup Gruyere, 1/4 cup cheddar, 1/4 cup Parmesan, and panko breadcrumbs. Sprinkle evenly over the squash mixture.
14. Step 14: Bake for 20-25 minutes until the topping is golden brown and bubbly.
15. Step 15: Remove from oven and let rest for 5-10 minutes before serving.
16. Step 16: Garnish with chopped fresh parsley, if desired, and serve hot.

Tips & Variations

• For a richer flavor, substitute half the milk with heavy cream.
• Try adding cooked bacon or sautéed mushrooms for extra texture and taste.
• Use gluten-free flour and breadcrumbs to make this dish gluten-free.
• Swap Gruyere with mozzarella for a milder cheese flavor.

Storage

Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven at 350°F (175°C) until warmed through to maintain a crispy topping. Avoid microwaving to prevent sogginess.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I prepare this dish ahead of time?

Yes, you can assemble the dish a day in advance and refrigerate it. Bake just before serving, adding a few extra minutes if starting cold from the fridge.

How do I know when the spaghetti squash is done roasting?

The squash is done when the flesh is tender and easily pierced with a fork. Roasting time typically ranges from 45 to 60 minutes depending on size.

Spaghetti Squash Au Gratin Recipe

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★★★★★

4.9 from 116 reviews

Spaghetti Squash Au Gratin is a delicious and healthy twist on the classic au gratin dish, featuring tender roasted spaghetti squash tossed in a creamy cheese sauce made with Gruyere, sharp cheddar, and Parmesan, topped with a golden breadcrumb crust. This comforting casserole is perfect as a nutritious side or a satisfying vegetarian main course.

• Author: Emma
• Prep Time: 20 minutes
• Cook Time: 1 hour 15 minutes
• Total Time: 1 hour 35 minutes
• Yield: 6 servings 1x
• Category: Side Dish
• Method: Baking
• Cuisine: American
• Diet: Vegetarian

Ingredients

Scale 1x2x3x

Spaghetti Squash

• 1 large spaghetti squash (about 3–4 pounds)
• 2 tablespoons unsalted butter, melted (for squash)
• Salt and pepper, to taste

Creamy Cheese Sauce

• 2 tablespoons unsalted butter
• 1 medium yellow onion, finely chopped
• 2 cloves garlic, minced
• 4 tablespoons all-purpose flour
• 3 cups whole milk
• 1/2 teaspoon salt
• 1/4 teaspoon black pepper
• 1/4 teaspoon nutmeg
• 3/4 cup grated Gruyere cheese
• 3/4 cup grated sharp cheddar cheese
• 1/4 cup grated Parmesan cheese

Topping

• 1/4 cup grated Gruyere cheese
• 1/4 cup grated sharp cheddar cheese
• 1/4 cup grated Parmesan cheese
• 1/4 cup panko breadcrumbs

Garnish (optional)

• 2 tablespoons chopped fresh parsley

Instructions

1. Preheat the Oven: Preheat your oven to 400°F (200°C) to prepare for roasting the spaghetti squash.
2. Prepare the Squash: Cut the spaghetti squash in half lengthwise and scoop out the seeds and stringy bits to create hollow halves.
3. Season the Squash: Drizzle the cut sides of each squash half with 2 tablespoons of melted butter, then sprinkle generously with salt and pepper to enhance flavor during roasting.
4. Roast the Squash: Place the squash halves cut-side down on a parchment-lined baking sheet. Roast for 45-60 minutes or until the flesh is tender and easily pierced by a fork.
5. Shred the Squash: Once cooled enough to handle, use a fork to scrape the flesh into spaghetti-like strands. Set this aside for the sauce mixture.
6. Melt Butter: In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter to prepare the base of the cheese sauce.
7. Sauté Onion and Garlic: Add the finely chopped onion to the melted butter and cook until softened and translucent, about 5-7 minutes. Add the minced garlic and sauté for an additional minute until fragrant.
8. Make a Roux: Sprinkle the all-purpose flour over the onion and garlic mixture. Cook, stirring constantly, for 1-2 minutes to form a roux that will thicken the sauce.
9. Whisk in Milk: Gradually add the whole milk to the roux, whisking continuously to prevent lumps and create a smooth sauce.
10. Simmer the Sauce: Bring the sauce to a gentle simmer over medium heat. Stir constantly, then reduce the heat to low and continue to simmer for 5-7 minutes until slightly thickened.
11. Season the Sauce: Stir in salt, black pepper, and nutmeg. Taste and adjust seasonings as needed to ensure balanced flavor.
12. Add Cheese: Remove the saucepan from heat and stir in 3/4 cup each of Gruyere and cheddar cheeses and 1/4 cup Parmesan until fully melted and the sauce is smooth and creamy. Reserve the remaining cheeses for topping.
13. Combine Squash and Sauce: Gently fold the shredded spaghetti squash into the cheese sauce, ensuring even coating without breaking the strands too much.
14. Transfer to Baking Dish: Pour the cheesy spaghetti squash mixture into a greased 9×13 inch baking dish, spreading evenly.
15. Prepare the Topping: In a small bowl, mix remaining 1/4 cup each of Gruyere, cheddar, Parmesan cheeses, and 1/4 cup panko breadcrumbs to create a crunchy cheesy crust.
16. Sprinkle the Topping: Evenly distribute the breadcrumb and cheese mixture over the top of the casserole.
17. Bake Au Gratin: Bake in the preheated oven for 20-25 minutes until the topping is golden brown and bubbling, indicating the cheese is melted and crispy.
18. Rest Before Serving: Remove from oven and let the dish rest for 5-10 minutes to set and cool slightly for easier serving.
19. Garnish and Serve: Optionally sprinkle chopped fresh parsley over the top for a fresh finish. Serve hot and enjoy your creamy, cheesy spaghetti squash au gratin!

Notes

• You can substitute whole milk with 2% milk or a lactose-free alternative if desired, but whole milk gives the best creamy texture.
• Use freshly grated cheeses for the best melting and flavor results.
• If you prefer a spicier version, add a pinch of cayenne pepper or smoked paprika to the cheese sauce.
• Panko breadcrumbs provide a light, crispy topping, but you can use regular breadcrumbs if needed.
• Make sure to cool the roasted squash enough before shredding and mixing with the sauce to avoid curdling or splitting the cheese sauce.
• This dish can be made ahead and reheated; cover with foil and bake at 350°F (175°C) until warmed through.

Keywords: spaghetti squash, au gratin, healthy casserole, cheese sauce, roasted vegetables, vegetarian side dish