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Spaghetti Squash Au Gratin Recipe

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3.9 from 88 reviews

This Spaghetti Squash Au Gratin is a delicious and healthy alternative to traditional cheesy casseroles. Featuring tender roasted spaghetti squash smothered in a creamy, cheesy sauce made from Gruyere, sharp cheddar, and Parmesan cheeses, then topped with a crispy golden breadcrumb crust, this dish makes a comforting vegetarian main or side. It’s low in calories compared to potato or pasta gratins and packed with flavor, perfect for a nutritious family dinner or special occasion meal.

Ingredients

Squash

  • 1 large spaghetti squash (about 3-4 pounds)
  • 2 tablespoons unsalted butter, melted (for roasting)
  • 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 (plus 1/4 cup reserved for topping)
  • 3/4 cup grated sharp cheddar cheese (plus 1/4 cup reserved for topping)
  • 1/4 cup grated Parmesan cheese (plus 1/4 cup reserved for topping)

Topping

  • 1/4 cup panko breadcrumbs
  • 2 tablespoons chopped fresh parsley (optional, for garnish)

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 in half lengthwise and scoop out all seeds and stringy bits to create clean halves.
  3. Season the squash: Drizzle the cut sides with 2 tablespoons melted butter and generously sprinkle with salt and black pepper for flavor.
  4. Roast the squash: Place the halves cut-side down on a parchment-lined baking sheet and roast for 45-60 minutes until the flesh is tender and easily pierced with a fork.
  5. Shred the squash: Once cool enough to handle, use a fork to shred the roasted flesh into spaghetti-like strands and set aside.
  6. Melt the butter: In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter in preparation for the sauce.
  7. Sauté onion and garlic: Add the finely chopped onion to the melted butter and cook about 5-7 minutes until translucent; then add minced garlic and cook an additional minute until fragrant.
  8. Make a roux: Sprinkle the flour over the onion and garlic mixture and cook, stirring constantly for 1-2 minutes to form a light roux that will thicken the sauce.
  9. Whisk in the milk: Gradually add the milk in small portions, whisking constantly to prevent lumps and create a smooth sauce.
  10. Simmer the sauce: Bring the sauce to a simmer over medium heat while stirring, then reduce to low and cook for 5-7 minutes until slightly thickened.
  11. Season the sauce: Stir in salt, pepper, and nutmeg. Taste and adjust seasonings as needed.
  12. Add cheese: Remove from heat and stir in 3/4 cup Gruyere, 3/4 cup sharp cheddar, and 1/4 cup Parmesan until all cheeses have melted and the sauce is creamy and smooth. Reserve remaining cheese for topping.
  13. Combine squash and sauce: Gently fold the shredded spaghetti squash into the cheese sauce until well combined.
  14. Transfer to baking dish: Pour the mixture evenly into a greased 9×13 inch baking dish.
  15. Prepare the topping: In a small bowl, mix the reserved 1/4 cup Gruyere, 1/4 cup cheddar, 1/4 cup Parmesan, and panko breadcrumbs.
  16. Sprinkle the topping: Evenly distribute the cheese and breadcrumb topping over the squash mixture for a crispy finish.
  17. Bake the au gratin: Place in the preheated oven and bake for 20-25 minutes until the topping is golden brown and bubbly.
  18. Let it rest: Remove from oven and allow to rest for 5-10 minutes to set before serving.
  19. Garnish and serve: Optionally garnish with chopped fresh parsley for color and fresh flavor. Serve warm and enjoy!

Notes

  • Don’t overcook the spaghetti squash as it can become mushy and lose its texture.
  • Using high-quality cheeses greatly enhances the flavor of the gratin.
  • Season the sauce to your taste—feel free to add extra salt, pepper, or nutmeg.
  • You can assemble the dish ahead of time and refrigerate for up to 24 hours; increase baking time by a few minutes if baking cold.
  • For a spicy kick, add a pinch of red pepper flakes to the cheese sauce.
  • Experiment with different cheeses like Fontina, Mozzarella, or Asiago for varied flavors.

Find it online: https://flavorspath.com/spaghetti-squash-au-gratin-recipe/