Spaghetti Squash Au Gratin
A creamy, cheesy comfort food featuring tender spaghetti squash strands coated in rich Gruyere-cheddar sauce, topped with a golden breadcrumb crust. This healthy twist on classic au gratin delivers restaurant-quality flavor.
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
- Preparing the Spaghetti Squash:
- Preheat oven to 400°F (200°C).
- Cut spaghetti squash in half lengthwise and scoop out seeds. (Tip: Microwave whole squash for 2-3 minutes if too hard to cut.)
- Drizzle cut sides with 2 tablespoons melted butter, season with salt and pepper.
- Place halves cut-side down on parchment-lined baking sheet.
- Roast for 45-60 minutes until fork-tender.
- Let cool, then scrape flesh into spaghetti-like strands with a fork. Set aside.
- Making the Cheese Sauce:
- In large saucepan over medium heat, melt remaining 2 tablespoons butter.
- Add chopped onion and cook 5-7 minutes until soft and translucent.
- Add minced garlic and cook 1 minute until fragrant.
- Sprinkle flour over mixture, stirring constantly for 1-2 minutes to create a roux.
- Gradually whisk in milk, starting with small amounts to prevent lumps.
- Bring to simmer over medium heat, stirring constantly.
- Reduce heat to low and simmer 5-7 minutes until sauce thickens.
- Remove from heat and season with salt, pepper, and nutmeg.
- Stir in 3/4 cup Gruyere, 3/4 cup cheddar, and 1/4 cup Parmesan until melted and smooth.
- Assembling and Baking:
- Add shredded spaghetti squash to cheese sauce, folding gently to combine.
- Pour mixture into greased 9x13 inch baking dish.
- In small bowl, combine remaining cheeses with panko breadcrumbs.
- Sprinkle topping evenly over squash mixture.
- Bake at 400°F for 20-25 minutes until golden brown and bubbly.
- Let rest 5-10 minutes before serving.
- Garnish with fresh parsley if desired.
Notes
Storage: Store leftovers in airtight container in refrigerator for 3-4 days. Reheat in oven at 350°F for 15-20 minutes or microwave for 2-3 minutes.
Freezing: Freeze assembled au gratin (without breadcrumb topping) for up to 2 months. Thaw overnight, add fresh topping, and bake as directed.
Make-Ahead: Assemble completely, cover with foil, and refrigerate up to 24 hours. Add 5-10 minutes to baking time.
Cheese Tips: Use block cheese and grate yourself for best melting. Pre-shredded cheese contains anti-caking agents that create grainy texture.
Variations: Add cooked bacon, ham, or sausage for protein
Mix in sautéed mushrooms or wilted spinach
Substitute pepper jack for spicy version
Use gluten-free flour and breadcrumbs for gluten-free option Vegetarian Note: Check that Parmesan doesn't contain animal rennet if making vegetarian.
Freezing: Freeze assembled au gratin (without breadcrumb topping) for up to 2 months. Thaw overnight, add fresh topping, and bake as directed.
Make-Ahead: Assemble completely, cover with foil, and refrigerate up to 24 hours. Add 5-10 minutes to baking time.
Cheese Tips: Use block cheese and grate yourself for best melting. Pre-shredded cheese contains anti-caking agents that create grainy texture.
Variations: Add cooked bacon, ham, or sausage for protein
Mix in sautéed mushrooms or wilted spinach
Substitute pepper jack for spicy version
Use gluten-free flour and breadcrumbs for gluten-free option Vegetarian Note: Check that Parmesan doesn't contain animal rennet if making vegetarian.