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Cheesy Baked Spaghetti Squash Au Gratin Recipe

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★★★★★

4.5 from 71 reviews

This creamy and cheesy Spaghetti Squash Au Gratin is a comforting vegetarian dish that combines roasted spaghetti squash strands with a rich three-cheese sauce, then topped with a golden breadcrumb crust. It’s an elegant, low-carb alternative to traditional pasta dishes, baked to bubbly perfection with Gruyere, cheddar, and Parmesan cheeses.

Ingredients

Scale

Spaghetti Squash

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

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

  • 2 tablespoons chopped fresh parsley (optional)

Instructions

  1. Preheat the oven: Set your oven to 400°F (200°C) to prepare for roasting the spaghetti squash.
  2. Prepare the squash: Cut the spaghetti squash lengthwise in half and scoop out the seeds and stringy bits from the center.
  3. Season the squash: Drizzle the cut sides of the squash with 2 tablespoons of melted butter, then sprinkle generously with salt and black pepper for flavor.
  4. Roast the squash: Place the squash halves cut-side down on a parchment-lined baking sheet and roast in the oven for 45-60 minutes until the flesh is tender and easily pierced with a fork.
  5. Shred the spaghetti squash: Once cool enough to handle, use a fork to scrape out the flesh into long, spaghetti-like strands; set aside.
  6. Melt butter for sauce: In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter to prepare for making the cheese sauce.
  7. Sauté onion and garlic: Add the finely chopped onion to the melted butter and cook for 5-7 minutes until softened and translucent. Add minced garlic and cook for an additional minute until fragrant.
  8. Make a roux: Sprinkle the flour over the onion and garlic mixture and stir constantly for 1-2 minutes to cook out the raw flour taste and form a roux.
  9. Whisk in milk: Gradually add the whole milk a little at a time while whisking constantly to avoid lumps. Continue whisking until the sauce is smooth.
  10. Simmer the sauce: Bring the sauce to a gentle simmer over medium heat, stirring constantly. Reduce the heat and let it simmer for 5-7 minutes until it thickens slightly.
  11. Season the sauce: Stir in salt, black pepper, and nutmeg. Taste and adjust seasonings as needed to balance flavors.
  12. Add the cheese: Remove the saucepan from heat and stir in 3/4 cup Gruyere, 3/4 cup cheddar, and 1/4 cup Parmesan cheese until melted and the sauce is creamy and smooth. Reserve the remaining cheese for topping.
  13. Combine squash and sauce: Gently fold the shredded spaghetti squash into the cheese sauce until well coated.
  14. Transfer to baking dish: Pour the cheesy squash mixture into a greased 9×13 inch baking dish, spreading evenly.
  15. Prepare the topping: In a small bowl, mix the remaining 1/4 cup Gruyere, 1/4 cup cheddar, 1/4 cup Parmesan, and panko breadcrumbs to create the crispy topping.
  16. Sprinkle the topping: Evenly distribute the cheese and breadcrumb mixture over the top of the squash in the baking dish.
  17. Bake the au gratin: Bake in the preheated oven for 20-25 minutes until the topping turns golden brown and bubbly.
  18. Let it rest: Remove from the oven and allow to rest for 5-10 minutes to set before serving.
  19. Garnish and serve: Optionally sprinkle chopped fresh parsley over the top for a pop of color and freshness. Serve hot and enjoy!

Notes

  • Be sure not to overcook the squash, as it should shred easily but not become mushy.
  • The sauce can be prepared ahead and refrigerated; reheat gently before combining with the squash.
  • If you prefer a dairy-free version, substitute butter and milk with plant-based alternatives and use vegan cheeses.
  • Panko breadcrumbs add a nice crunchy texture, but you can omit if gluten-free is desired.
  • Leftovers can be stored in the refrigerator for 3-4 days and reheated in the oven to maintain crispiness.

Keywords: spaghetti squash, au gratin, cheesy casserole, vegetarian, low carb, baked squash, Gruyere cheese, cheddar cheese, Parmesan, comfort food

Find it online: https://todayfoodrecipe.com/cheesy-baked-spaghetti-squash-au-gratin-recipe/