Spaghetti Squash Au Gratin (Printable)

Tender roasted squash in a creamy, cheesy sauce baked to golden perfection.

# What You'll Need:

→ Vegetables

01 - 1 large spaghetti squash (about 3 lbs)
02 - 2 tablespoons olive oil
03 - 1 small yellow onion, finely chopped
04 - 2 cloves garlic, minced

→ Dairy & Cheese

05 - 1 cup shredded Gruyère cheese
06 - 1/2 cup grated Parmesan cheese
07 - 1/2 cup sour cream
08 - 2 tablespoons unsalted butter
09 - 1/4 cup milk (whole or 2%)

→ Spices & Seasoning

10 - 1/2 teaspoon salt
11 - 1/4 teaspoon ground black pepper
12 - 1/4 teaspoon ground nutmeg
13 - 1 tablespoon chopped fresh parsley (optional, for garnish)

# Directions:

01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - Cut the spaghetti squash in half lengthwise and scoop out the seeds. Drizzle the cut sides with 1 tablespoon olive oil and sprinkle with salt and pepper.
03 - Place the squash halves cut-side down on the prepared baking sheet. Roast for 35–40 minutes, until the flesh is tender and easily shredded with a fork.
04 - While the squash is roasting, heat the remaining 1 tablespoon olive oil and the butter in a skillet over medium heat. Add the onion and cook until soft and translucent, about 5 minutes. Add the garlic and cook for 1 minute more.
05 - Remove the squash from the oven. Allow to cool slightly, then use a fork to scrape the flesh into spaghetti-like strands. Place the strands in a large mixing bowl.
06 - Add the cooked onion and garlic, sour cream, milk, half the Gruyère, half the Parmesan, nutmeg, salt, and pepper to the bowl. Mix until well combined.
07 - Transfer the mixture to a greased 2-quart baking dish. Top with the remaining Gruyère and Parmesan.
08 - Reduce oven temperature to 375°F. Bake for 20–25 minutes, until the top is golden and bubbly.
09 - Garnish with chopped parsley before serving, if desired.

# Expert Advice:

01 -
  • You get all the creamy cheesy comfort of a gratin without the heavy pasta coma afterward
  • The squash naturally creates perfect strands that hold onto sauce remarkably well
  • It reheats beautifully for lunch the next day if you are lucky enough to have leftovers
02 -
  • Cutting raw spaghetti squash can be tricky. Microwave it for 2 to 3 minutes first to soften slightly, then use a sharp knife and steady pressure.
  • Do not skip cooling the squash before scraping. Hot squash turns to mush and you lose those gorgeous strand formations.
  • The sauce might look thin going into the baking dish but trust the process. It thickens beautifully in the oven.
03 -
  • Roast the squash a day ahead and keep the strands refrigerated. This cuts active cooking time in half on busy weeknights.
  • Use a box grater to shred your own cheese instead of buying pre shredded. The anti caking agents in bagged cheese prevent smooth melting.

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