Here’s a way to indulge in the flavors of classic French onion soup—imagine sweet, caramelized onions, nutty Gruyère, and a touch of Parmesan—transformed into a comforting dish that is perfect for any occasion!
Whether you’re hosting a cozy dinner party, whipping up an impressive weeknight meal, or meal-prepping for the week ahead, this French Onion Spaghetti Squash delivers rich, savory flavor with a healthier twist.
The magic happens with simple, wholesome ingredients, and the cooking process is as satisfying as the result. Roasting the squash creates tender, spaghetti-like strands that are low in carbs and soak up every bit of the cheesy, oniony goodness. Caramelizing the onions adds depth, while Gruyère and Parmesan bring an irresistible, melty finish. Plus, everything cooks right in the squash for minimal cleanup—because who doesn’t love a one-dish wonder?
Here’s a Joyful pro tip: Before slicing the squash (which tends to be a bit scary! Am I right?), pop it in the microwave for 4–5 minutes to soften it up. Not only does this make it much easier to cut in half, but it also ensures the squash cooks more evenly in the oven and shaves time off the roasting process. It’s a simple trick that I use all the time…it makes a big difference!
If you’re feeling creative, take it up a notch with a handful of sautéed spinach or kale for added greens, crispy bacon for indulgence, or even cooked chicken or tofu for a protein boost. And for a different presentation spin, you can transform this dish into a bubbling casserole by layering the ingredients in a baking dish (see notes below for more information on these variations).
This recipe is a way to enjoy the comforting flavors of French onion soup in a healthier yet decadent format—perfect for any occasion. I’m excited to share it with you!
Looking for more spaghetti squash recipes? Try my Spaghetti Squash with Creamy Hummus and Spinach Artichoke Dip Spaghetti Squash!
French Onion Spaghetti Squash
Indulge in the cozy flavors of French onion soup—caramelized onions, nutty Gruyère, and Parmesan—transformed into a comforting dish for any occasion!
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Preheat the Oven to 400°F (200°C). Microwave the spaghetti squash for 4–5 minutes to soften it slightly, making it easier to cut. Let it slightly cool, and carefully cut the squash evenly in half lengthwise. Scoop out the seeds and any stringy bits, then discard.
Drizzle the inside of each squash half with 1–2 teaspoons of olive oil (or lightly mist with oil spray). Sprinkle with salt and black pepper. Place the halves “cut-side down” on a baking sheet and roast for 25–30 minutes, or until the flesh is tender and easily scraped into spaghetti-like strands with a fork. *Tip: Roast time may vary depending on the size of your squash. Start checking at the 25-minute mark by gently scraping one half with a fork. If the strands aren’t soft and tender yet, return it to the oven for 5 more minutes or so until perfectly cooked.
While the squash roasts, caramelize the onions. Heat the remaining 1 Tbsp olive oil in a large skillet over medium heat. Add the thinly sliced onion and a pinch of salt. Cook, stirring every few minutes, for 8–10 minutes or until the onions are deeply browned and caramelized. Be careful not to burn them; lower the heat if necessary.
Remove the squash from the oven and carefully flip the halves over—they’ll be very, very hot, so use a kitchen towel or flexible oven mitt for safety. Use a fork to scrape and fluff the interior, creating spaghetti-like strands.
Assemble and Bake: Divide the caramelized onions and grated Gruyère evenly between the two squash halves, mixing them gently with the squash strands in each spaghetti squash shell. Sprinkle each half with 1 tablespoon of Parmesan cheese. Return the squash to the oven and bake for an additional 10 minutes, until the cheese is melted and bubbly. Garnish with optional minced parsley or thyme and enjoy!
Variations to try:
Cheese swaps: you can use Swiss cheese instead of Gruyère or add mozzarella for extra gooeyness.
Boost the protein by add cooked pieces of chicken or tofu.
Add a handful of sautéed spinach or kale with the onions for added greens and extra nutrition.
Increase the indulgence by mixing in 1 to 2 tablespoons of crispy, cooked bacon.
You can transform this dish into a casserole by scooping the spaghetti squash strands into a baking dish, layering with the onion-cheese mixture, and baking until it’s warmed through, and the cheese is melty.
Sprinkle with a touch of smoked paprika or garlic powder for an extra flavor punch.
Serving Size: 0.5 spaghetti squashCalories: 360Carbohydrates: 26gProtein: 12gTotal Fat: 24g— Unsaturated Fat: 20g— Saturated Fat: 8gCholesterol: 35mgSodium: 900mgPotassium: 474mgFiber: 5gTotal Sugar: 10g— Natural Sugar: 10g— Added Sugar: 0gVitamin A: 647IUVitamin C: 15mgCalcium: 394mg
Nutrition information is calculated using a leading industry software. That being said, brands can vary, and there may be slight fluctuations in the numbers.