Spaghetti Squash Au Gratin
Creamy, cheesy spaghetti squash au gratin with Gruyere, cheddar, and Parmesan. A healthier take on classic comfort food with a golden breadcrumb topping.
Ingredients
- For the Spaghetti Squash:
- 1 large spaghetti squash about 3-4 pounds
- 2 tablespoons unsalted butter melted
- Salt and black pepper to taste
- For the 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 plus more to taste
- 1/4 teaspoon black pepper plus more to taste
- 1/4 teaspoon nutmeg
- 3/4 cup grated Gruyere cheese
- 3/4 cup grated sharp cheddar cheese
- 1/4 cup grated Parmesan cheese
- For the 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
- For Garnish:
- 2 tablespoons fresh parsley chopped, optional
Instructions
- Preparing the Spaghetti Squash:
- Preheat oven to 400°F (200°C).
- Cut the spaghetti squash in half lengthwise. If too hard, microwave for 2-3 minutes to soften. Scoop out seeds and stringy bits.
- Drizzle each half with 2 tablespoons melted butter. Season generously with salt and pepper.
- Place squash halves cut-side down on a parchment-lined baking sheet. Roast for 45-60 minutes until tender and easily pierced with a fork.
- Let cool for 10 minutes. Use a fork to scrape the flesh into spaghetti-like strands. Transfer to a large bowl and set aside.
- Making the Cheese Sauce:
- In a large saucepan over medium heat, melt the remaining 2 tablespoons butter.
- Add chopped onion and cook for 5-7 minutes until softened and translucent.
- Add minced garlic and cook for 1 minute, stirring constantly, until fragrant.
- Sprinkle flour over the onion and garlic. Stir constantly for 1-2 minutes to create a roux.
- Gradually whisk in milk, about 1/2 cup at a time, whisking vigorously after each addition to prevent lumps.
- Bring sauce to a gentle simmer over medium heat, stirring constantly. Reduce heat to low and simmer for 5-7 minutes until thickened.
- Season with salt, pepper, and nutmeg. Taste and adjust seasonings.
- Remove from heat. 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 the cheese sauce. Fold gently to coat every strand evenly.
- Pour mixture into a greased 9x13 inch baking dish. Spread evenly with a spatula.
- In a small bowl, combine remaining cheeses and panko breadcrumbs. Sprinkle evenly over the squash mixture.
- Bake at 400°F for 20-25 minutes until topping is golden brown and sauce is bubbling around the edges.
- Remove from oven and let rest for 5-10 minutes. Garnish with chopped fresh parsley if desired. Serve hot.
Notes
Make-Ahead Instructions: Assemble the dish completely up to 24 hours in advance. Cover tightly with plastic wrap and refrigerate. Add 5-10 minutes to baking time when cooking from cold.
Storage: Store leftovers in an airtight container in the refrigerator for 3-4 days. Reheat in the oven at 350°F for 15-20 minutes (covered with foil) or microwave individual portions for 1-2 minutes.
Cheese Substitutions: Swiss cheese can replace Gruyere. Fontina or smoked gouda also work well. For a budget-friendly option, use all cheddar.
Gluten-Free Option: Use a 1:1 gluten-free flour blend in place of all-purpose flour for the roux.
Protein Additions: Stir in cooked bacon bits, diced ham, or shredded rotisserie chicken to make it a complete main course.
Don't Overcook the Squash: Check for doneness at 45 minutes. Overcooked squash becomes mushy and watery.
Use Freshly Grated Cheese: Pre-shredded cheese contains anti-caking agents that prevent smooth melting. Grate your own for best results.
Prevent Grainy Sauce: Always remove the pan from heat before adding cheese to prevent it from becoming grainy or separating.
Freezing: Can be frozen for up to 2 months in an airtight container. Thaw overnight in refrigerator before reheating.
Storage: Store leftovers in an airtight container in the refrigerator for 3-4 days. Reheat in the oven at 350°F for 15-20 minutes (covered with foil) or microwave individual portions for 1-2 minutes.
Cheese Substitutions: Swiss cheese can replace Gruyere. Fontina or smoked gouda also work well. For a budget-friendly option, use all cheddar.
Gluten-Free Option: Use a 1:1 gluten-free flour blend in place of all-purpose flour for the roux.
Protein Additions: Stir in cooked bacon bits, diced ham, or shredded rotisserie chicken to make it a complete main course.
Don't Overcook the Squash: Check for doneness at 45 minutes. Overcooked squash becomes mushy and watery.
Use Freshly Grated Cheese: Pre-shredded cheese contains anti-caking agents that prevent smooth melting. Grate your own for best results.
Prevent Grainy Sauce: Always remove the pan from heat before adding cheese to prevent it from becoming grainy or separating.
Freezing: Can be frozen for up to 2 months in an airtight container. Thaw overnight in refrigerator before reheating.