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Delicious Spaghetti Squash Gratin baked with cheese and herbs

Spaghetti Squash Gratin

A comforting gratin featuring delicate strands of spaghetti squash bound in a creamy, nutmeg-kissed cheese sauce, topped with a crisp, golden crust.
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Prep Time 20 minutes
Cook Time 1 hour 25 minutes
Total Time 1 hour 45 minutes
Servings: 6 servings
Course: Main Course, Side Dish
Cuisine: American, Vegetarian
Calories: 400
Ingredients Method Notes

Ingredients
  

Main Ingredients
  • 1 large spaghetti squash (about 3-4 pounds) Choose a firm, heavy squash with a hard rind.
  • 4 tablespoons unsalted butter, divided 2 tablespoons for roasting squash, 2 tablespoons for sauce.
  • 1 medium yellow onion, finely chopped
  • 2 cloves garlic, minced
  • 4 tablespoons all-purpose flour For roux.
  • 3 cups whole milk Can substitute with 2% for a lighter version.
  • 1/2 teaspoon salt, plus more to taste Adjust seasoning at the end.
  • 1/4 teaspoon black pepper, plus more to taste
  • 1/4 teaspoon nutmeg Adds warmth to the sauce.
  • 1 cup grated Gruyere cheese, divided 3/4 cup for sauce, 1/4 cup for topping.
  • 1 cup grated sharp cheddar cheese, divided 3/4 cup for sauce, 1/4 cup for topping.
  • 1/2 cup grated Parmesan cheese, divided 1/4 cup for sauce, 1/4 cup for topping.
  • 1/4 cup panko breadcrumbs For a crispy topping.
  • 2 tablespoons chopped fresh parsley, for garnish (optional) Adds freshness.

Method
 

Preparation
  1. Preheat oven to 400°F (200°C). Halve spaghetti squash lengthwise and scoop out seeds.
  2. Brush cut sides with 2 tablespoons melted butter and season with salt and pepper.
  3. Place halves cut-side down on a parchment-lined baking sheet and roast for 45–60 minutes until flesh yields easily to a fork.
  4. Remove and let cool slightly, then shred flesh into long strands with a fork.
Sauce Preparation
  1. In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter.
  2. Add onion and garlic, cooking gently until onion is soft and translucent—about 6–8 minutes.
  3. Sprinkle flour to form a roux, stirring constantly for 1–2 minutes to cook raw flour taste out.
  4. Gradually whisk in milk, smoothing out lumps and bringing mixture to a gentle simmer.
  5. Cook, stirring, until sauce thickens enough to coat the back of a spoon. Season with salt, black pepper, and nutmeg.
  6. Stir in 3/4 cup of Gruyere, cheddar, and 1/4 cup of Parmesan until melted.
Assembly and Baking
  1. Fold shredded squash into the cheese sauce until evenly coated.
  2. Transfer mixture into a greased baking dish, smoothing the top.
  3. Combine remaining cheeses with panko breadcrumbs and scatter over gratin.
  4. Bake for 20–25 minutes until topping is golden. Let rest for 5–10 minutes before serving.

Notes

For a crispier topping, mix a teaspoon of melted butter into the panko before scattering. Allow the gratin to rest before slicing for cleaner servings.