Spaghetti Squash Au Gratin

Spaghetti squash au gratin brings together comfort food and healthy eating in the most delicious way and is perfect for feeding a family or impressing guests at a potluck. You get all the creamy richness of a traditional gratin but with the wholesome swap of spaghetti squash for pasta.

I often make this when I find a beautiful squash at the farmers market and my family always asks for seconds. I made this one chilly autumn weekend when squash was everywhere and honestly it was gone before I even got a second serving. It quickly became a favorite for cozy dinners and potlucks.

Gather Your Ingredients

• Spaghetti squash: Tender and mild base while cutting down on carbs compared to pasta. Select a firm squash with no soft spots and a bright yellow skin.
• Unsalted butter: Adds richness to both the roasting and the sauce. Opt for a high-quality butter for the best flavor.
• Yellow onion: Delivers a sweet depth that builds the flavor foundation of the cheese sauce. Look for a firm onion with no sprouting ends.
• Fresh garlic: Gives a fragrance and zing that is essential. Choose plump cloves and avoid any that feel soft.
• All-purpose flour: Thickens the sauce to create that classic creamy gratin texture. Make sure it is not expired for best thickening.
• Whole milk: Keeps the sauce creamy without being heavy. The full-fat milk helps the cheese melt smoothly.
• Salt and black pepper: Balance all the flavors. Freshly cracked pepper really elevates the cheese sauce.
• Nutmeg: Brings a subtle warmth perfect for creamy dishes. Freshly grated nutmeg is especially aromatic.
• Gruyere cheese: Melts beautifully and gives a nutty complex taste. Buy a block and grate it yourself for freshness.
• Sharp cheddar cheese: Adds a familiar crave-worthy tang. White or yellow both work.
• Parmesan cheese: Gives extra savory punch and a crisp top when mixed with breadcrumbs.
• Panko breadcrumbs: Lend crunch to the golden topping. Look for the flaky Japanese style for the best texture.
• Fresh parsley (optional): For garnish brings color and a little fresh finish. Flat-leaf parsley is best.

How to Make It

Prepare the Squash:

Slice the squash lengthwise with a sturdy knife and remove the seeds and any stringy parts inside. Use a spoon to scrape it clean but keep as much flesh as possible for maximum yield.

Roast the Squash:

Melt two tablespoons of butter and brush generously over the cut sides of the squash. Add a light sprinkling of salt and black pepper. Place the squash cut side down on a parchment-lined baking sheet. Bake in a hot oven at four hundred degrees until the squash is tender and easily pierced with a fork, which usually takes forty five to sixty minutes depending on the squash size.

Shred the Squash:

Let the squash cool just enough to handle. Using a fork pull the flesh into long noodle-like strands. Transfer all the squash into a bowl and set aside. Be sure not to mash the strands.

Make the Cheese Sauce:

Melt the remaining butter in a wide saucepan over medium heat. Add the finely chopped onion and sweat until soft and translucent, about six minutes. Add the minced garlic and stir for another minute. Sprinkle flour over the onions and cook, stirring constantly, for two minutes. Gradually add milk, whisking well after each addition. Bring to a gentle simmer and let thicken for about six minutes. Off the heat, stir in salt, pepper, and nutmeg. Taste and adjust seasoning.

Melt in Cheese:

Add three quarters of the Gruyere and cheddar cheeses plus a quarter cup Parmesan to the hot sauce. Stir until melted and smooth. Reserve the rest for the topping.

Combine Squash and Sauce:

Fold the spaghetti squash strands into the cheese sauce. Stir gently to keep the strands intact.

Assemble in Baking Dish:

Lightly grease a nine by thirteen inch baking dish. Pour in the saucy squash and spread evenly.

Top with Cheese and Breadcrumbs:

Mix the reserved cheeses and panko in a small bowl. Scatter this mixture over the casserole.

Bake Until Golden:

Place the pan in a preheated oven and bake for twenty to twenty five minutes until the top is deeply golden and crisp around the edges.

Garnish and Serve:

Sprinkle chopped parsley over the finished gratin. Serve hot straight from the oven.

My favorite part is that nutty Gruyere layer blanketing the top. My family always gathers around when that aroma fills the kitchen and everyone tries to snag a crispy corner.

Flavor Boosters

Feel free to swap Gruyere for Swiss or Emmental for a similar melty flavor. Cheddar can be swapped for Colby or Monterey Jack if needed. For some smoky depth try adding a sprinkle of smoked paprika to the cheese sauce. For a dairy free option use plant-based butter and unsweetened cashew milk plus a melty vegan cheese. If you have gluten sensitivities replace flour and panko with a one to one gluten free blend and gluten free breadcrumbs.

Serving Suggestions

This gratin makes a fantastic vegetarian main paired with a leafy green salad. For a richer meal serve alongside roasted chicken or pan-seared salmon. At holiday gatherings it rounds out a buffet of hearty sides. I sometimes add a handful of crisped sage or bacon on top for a special touch.

Creative Twists

The French tradition of au gratin involves baking a dish with a browned crust often from cheese or breadcrumbs. Using spaghetti squash in place of potatoes or pasta modernizes the method and gives it a North American twist that fits today’s love of veggie forward cuisine. For seasonal changes, try butternut or acorn squash in winter, mushrooms in fall, or add asparagus in spring. Kids love shredding the squash, and it always disappears fast at potlucks. For freezer prep, portion out after baking, wrap well, and reheat in the oven for best texture.

Enjoy this cozy gratin for a nourishing, comforting meal. It truly brings everyone together around the table.

Frequently Asked Questions About This Recipe

→ How do I know when the spaghetti squash is fully roasted?

The squash is ready when it's easily pierced with a fork and the flesh pulls into spaghetti-like strands with little resistance.

→ Can other cheeses be used for the au gratin?

Yes, you can experiment with Swiss, mozzarella, or fontina if preferred, but Gruyere, cheddar, and Parmesan offer a balanced flavor.

→ What does the panko topping add to the dish?

Panko gives a crispy, golden crust, providing a pleasant contrast to the creamy interior of the gratin.

→ How can I make the dish lighter?

You can substitute low-fat milk and reduce the amount of cheese to lighten up the dish without sacrificing too much flavor.

→ Is this dish suitable for preparing in advance?

Yes, assemble the squash and sauce mixture ahead of time. Add the topping just before baking for best results.