Spaghetti Squash Casserole

My rich and creamy spaghetti squash casserole takes mild and delicate roasted spaghetti squash strands, and turns them into a hot, bubbly casserole filled with fall flavors. Prepared with a savory sauce kissed with Gruyere cheese, plus caramelized onions, lean ground turkey, garlic, spinach, fresh sage and thyme, this cheesy casserole gets a tasty topping of crispy, French fried onions for crunch and added flavor!

Spaghetti Squash Becomes a Cozy Casserole

As soon as late September/early October rolls around, and all of the delicious and colorful autumn squash varietals start to become abundant in the markets, I begin craving all sorts of yummy recipes making use of their colorful, sweet-savory, and delicate flesh.

Squash is so wonderfully versatile, that each and every year I find myself excited to create new recipes centered around one type of squash or another, and who can blame me?

The options are endless with these beauties, from soup preparations, to side dishes, to appetizers, to full-on entrees—so fun, and so delicious!

Since I'm still feeling pretty obsessed with spaghetti squash these days, I thought it'd be tasty and fun to prepare a deliciously warming and cozy casserole out of it, one that could play a role on our table throughout the fall and even through to the Thanksgiving holiday...

I wanted a dish that could stand alone as a a full-on entree, or even be a part of a larger spread as a unique side dish similar to a green bean casserole.

My spaghetti squash recipe is wonderfully rich and savory, prepared with a creamy sauce kissed with Gruyere cheese, plus an addition of caramelized onions mixed with browned, lean ground turkey, baby spinach, garlic, fresh sage and thyme leaves.

I even had to top things off with some crispy fried onion pieces for a tad more crunch and flavor!

So whether you enjoy this spaghetti squash casserole recipe on its own, as an entree on a cold fall evening, or rotate it in as a delectably tasty veggie-filled side on your Thanksgiving Day table, you'll find it completely irresistible...and utterly comfy-cozy!

My Recipe for Spaghetti Squash Casserole with Creamy Gruyere Sauce

Whether you're looking for lower-carb option for dinner, or simply want to incorporate more veggies into your meals, spaghetti squash is the perfect pick during autumn.

Once roasted, spaghetti squash can be fluffed with a fork to create spaghetti-like strands, and those can be combined with other ingredients, or sauces, in a similar way that traditional spaghetti or angel hair pasta would be.

While I often love to just combine my spaghetti squash with sauteed veggies and stuff everything back into the squash shell, I love this preparation of combining the strands with a creamy sauce plus a few other savory ingredients, then turning them out into a casserole dish, and baking things off with an additional topping of cheese and crispy, French-fried onions.

The result is rich, creamy, saucy, warming...and extra comforting!

Here's a sneak peek at how I make my spaghetti squash casserole: (or just jump to the full recipe...)

1. To get started, I halve and clean out my spaghetti squash of seeds, then season and drizzle on some olive oil.
2. Next, I roast the squash cut-side down on a baking sheet for about an hour, or until easily pierced with a skewer.
3. While my squash roasts, I prepare my creamy Gruyere sauce, as well as my caramelized onion and ground turkey mixture.
4. And once the squash is ready, using a fork, I pull/fluff the flesh away from the shell into long, spaghetti-like strands. I then combine the strands with the sauce and the turkey, onion, and sage mixture, and spoon everything into my prepared baking dish.
5. I add a small additional sprinkle of Gruyere cheese over top of the casserole, then bake uncovered for about 20 minutes.
6. After 20 minutes, I top the casserole with some crispy fried onion pieces, and bake for an additional 5 minutes to give the crispy onions a bit more color.
7. To finish my spaghetti squash casserole, I sprinkle over some fresh thyme leaves, and serve.

Recipe

Spaghetti Squash Casserole

by Ingrid Beer

Print Recipe

Brimming with fall flavors, this spaghetti squash casserole is prepared with a creamy Gruyere sauce and topped with crispy fried onions!

Category: Entree
Cuisine: American

Yield: Serves 8

Nutrition Info: 430 calories per serving

Prep Time: 25 minutes
Cook time: 1 hour 20 minutes
Total time: 1 hour 45 minutes

Casserole Ingredients:

• 2 (roughly 3 pound) spaghetti squash, halved and seeds discarded
• Olive oil
• Salt
• Black pepper
• ½ teaspoon granulated onion
• ½ teaspoon granulate garlic
• 1 medium onion, quartered and thinly sliced
• ½ pound ground turkey
• ¼ teaspoon white pepper
• 4 cloves garlic, pressed through garlic press
• 2 cups (packed) baby spinach leaves
• 1 ½ tablespoon chopped fresh sage leaves
• 1 teaspoon fresh thyme leaves, plus extra for garnish
• ¾ cup grated Gruyere cheese
• ½ cup crispy, French fried onions

Creamy Gruyere Sauce Ingredients:

• 3 tablespoons unsalted butter
• 2 cloves garlic, pressed through garlic press
• 5 tablespoons (level) flour (roughly 1 ½ ounces)
• 3 cups whole milk
• Salt
• Black pepper
• 1 teaspoon Italian seasoning
• Pinch nutmeg
• ¼ cup grated Gruyere cheese

Preparation:

1. Begin by gathering and prepping all of your casserole ingredients according to the ingredient list above to have ready and organized for use.
2. Preheat the oven to 400°, and line a large baking sheet with foil.
3. Drizzle a couple of tablespoons worth of the olive oil over the cut sides of the spaghetti squash, and sprinkle over a couple of generous pinches of salt and black pepper, as well as the granulated onion and garlic.
4. Place all four squash halves onto the baking sheet cut-side down, and roast for about 1 hour (or a little more if the squash are larger), or until they can easily be pierced with a skewer.
5. While the squash roasts, place a large, heavy-bottom skillet over medium-high heat, and drizzle in about 3 tablespoons of the olive oil. Once hot, add in the sliced onions, along with a couple of pinches of salt and pepper, and saute the onions for about 10 minutes, or until golden-brown.
6. Next, add the ground turkey into the onions, along with another pinch of salt and pepper, plus the white pepper, breaking it up with a spatula into a fine crumble. Cook that for about 2-3 minutes, or until the turkey becomes a deep golden-brown.
7. Next, stir in the garlic, followed by the spinach, and allow that to wilt into the turkey mixture for about 30 seconds to 1 minute. Stir in the sage and the thyme leaves, and spoon the mixture into a bowl. Set aside.
8. Once the spaghetti squash is tender, remove from oven and allow it to cool for about 20 minutes, just so that you can easily handle it. Turn the oven temperature down to 375°.
9. Then, using a fork, pull the squash flesh away from the shell, fluffing it a bit to create those spaghetti-like strands, and spoon those into a large bowl. Set aside for a moment.
10. Gather and prep all of your creamy Gruyere sauce ingredients according to the ingredient list above to have ready and organized for use.
11. To prepare the sauce, place a medium-large pot over medium heat, and add in the butter and garlic. Once the butter is melted, sprinkle in the flour, and using a whisk, whisk the flour into the melted butter to create a roux.
12. Slowly pour the milk into the roux, whisking all the while to avoid lumps from forming, and allow the sauce to come to a vigorous simmer and thicken up. Once the sauce begins to thicken, allow it to simmer for about 2-3 minutes more, to tighten up the sauce.
13. Turn off the heat, and sprinkle in a generous couple of pinches of salt, black pepper, the Italian seasoning, and the pinch of nutmeg. (Taste the sauce to see if additional salt is needed, as you want the sauce to be nice and savory since it'll be combined with a lots of spaghetti squash.)
14. Add in the ¼ cup grated Gruyere cheese and whisk to blend/melt it into the sauce.
15. To assemble the casserole, add the spaghetti squash strands directly into the sauce, along with the turkey/onion/spinach mixture. Using a large spoon, gently combine the sauce with the squash and turkey mixture, making sure that everything is well combined. Check to see if any additional salt or pepper is needed.
16. Next, lightly mist a 3 quart baking dish with cooking spray, and spoon the spaghetti squash mixture into it. Sprinkle over top the ¾ cup of grated Gruyere cheese, and place into the oven, uncovered, to bake for 20 minutes. After 20 minutes, sprinkle over top the French fried onions, and bake an additional 5 minutes.
17. To serve, garnish with thyme leaves, and enjoy.

Tips & Tidbits for my Spaghetti Squash Casserole recipe:

• Two smaller spaghetti squash for easier handling: If you can find a couple of (roughly) 3 pound spaghetti squash, with nice, bright yellow skin, opt for those as they will be a bit easier to halve and clean out. You can use a larger squash, but those tend to be a lot harder to cut, and handle. You'll need about 6 pounds of spaghetti squash, total.
• Vegetarian spaghetti squash casserole: This casserole is very easy to make completely vegetarian by simply omitting the ground turkey. Simply caramelize the onions with the rest of the aromatic ingredients, and leave out the turkey.
• Substitute your favorite protein: If you'd prefer to use a protein other than ground turkey, a great option is sweet or spicy Italian sausage. You can even add some chopped rotisserie chicken to this casserole with yummy results.
• Prepare this spaghetti squash casserole ahead: To keep things more streamlined on the day you'd like to serve this casserole, you can roast and scoop out the spaghetti squash strands a day or two ahead of time, and keep those in a covered container in the fridge. You can also prep the turkey and onion mixture, as well as the creamy sauce, and keep all of those components in covered containers in the fridge as well. Then, simply warm the sauce slightly, and combine and bake off the day you'd like to enjoy.

Hungry for more delicious squash recipes? Check out this Stuffed Acorn Squash, this Butternut Squash Casserole, this Pumpkin Soup with Sage Croutons, this Roasted Acorn Squash, or this Butternut Squash Soup!