This spaghetti squash gratin is a delicious side dish made with squash, milk, and Parmesan cheese. Perfect for fall and winter!
This fall, a friend dropped off lots of spaghetti squash at our front door.
After sharing some with family and friends, we still had a lot of spaghetti squash!
I couldn’t resist making a few batches of spaghetti squash marinara (and of course, tossing it with Parmesan).
But guys, I have to admit something.
Spaghetti squash might be the darling child of healthy eating fads, but I really think it tastes best when cooked with cheese. Don’t judge, just join me.
Recently, as I was testing (and retesting, and retesting) this recipe for a salmon spaghetti squash bake, I discovered my favorite technique for baking cheesy spaghetti squash.
This spaghetti squash gratin is creamy, cheesy, and makes a delicious, relatively healthy vegetable side dish.
How to Cook Spaghetti Squash
For this recipe, you can cook your squash however you prefer.
When it’s done cooking, use a fork to scrape the spaghetti-like strands out of the squash.
How to Make Spaghetti Squash Gratin
Take your cooked spaghetti squash strands and add them to a large, oven-safe pan with olive oil, garlic, salt, and red pepper flakes. I use this Lodge 12″ carbon steel skillet.
Cook the squash for a few minutes to help release some of the moisture.
Next, toss the squash with a little all-purpose flour. Gluten-free AP flour (such as Cup 4 Cup) will work perfectly.
When the squash has absorbed all the flour, you can move onto the next step.
Slowly pour in a cup and a half of milk.
Bring the milk to a simmer, and keep simmering until the liquid thickens.
It will seem like a lot of milk, but it’s going to thicken up quickly.
Carefully stir cheese into the squash, and then top it with more cheese.
I told you there would be cheese!
Carefully slide the pan into the oven and bake until the top is golden.
Spaghetti Squash Gratin
- 3 pounds spaghetti squash
- 3 tablespoons olive oil (divided), plus more for cooking the spaghetti squash
- 2 teaspoons garlic powder (or 2 garlic cloves, minced)
- 1 teaspoon sea salt, plus about one pinch of salt (for squash)
- ¼ teaspoons red pepper flakes
- 2 tablespoons flour Use AP gluten-free flour if needed
- 1 ½ cup milk
- ⅔ cup Parmesan, freshly grated (divided) Or substitute Swiss, Jarlsberg, or Smoked Gouda
Cook the Spaghetti Squash:
- Cook squash according to your desired preference. Oven Directions: Cut squash in half and remove the seeds. Drizzle with oil and a pinch of salt (if desired). Roast cut-side down on a baking sheet at 400°F for about 40 minutes, or until the squash is easily pierced with a fork.Pressure Cooker: See Instant Pot directions.Allow squash to cool slightly. Use a fork to scrape the spaghetti squash out of the peel.
Make the Casserole:
- Preheat oven to 400°F and move an oven rack to the top position (near the broiler).Heat 2 TB olive oil over medium heat in a large, oven-safe pan (like cast iron or carbon steel).Add the spaghetti squash, garlic, salt and red pepper flakes. Cook about 3 minutes to remove some of the moisture from the squash.
- Add the flour to the squash mixture and stir. Cook about 2 minutes until the flour is incorporated. Stir well and make sure there are no lumps of uncooked flour before proceeding.
- Slowly pour the milk into the pan, stirring as you pour. Continue cooking until the liquid begins to simmer and the milk begins to thicken.Simmer for about 2 minutes (or until the milk begins to thicken), and then stir in ½ cup of the cheese. Make Ahead Tip: If desired, you can stop at this point and finish cooking later. Make up to one day ahead, and then reheat to a simmer before proceeding to the next step.
- Sprinkle the remaining cheese across the top of the squash and drizzle with the remaining 1 TB oil.
- Carefully move the pan into the oven onto the top rack. Bake 13 minutes. Position the pan so that it's directly under the broiler. Turn on the broiler and cook for 2 more minutes, until the cheese is golden. (If your oven does not have a broiler, simply cook 2 more minutes.)Serve immediately.