Rosemary, Lemon & Caramelized Onion Spaghetti Squash Bake

The squash dish upon completion.

Within each treasured recipe is a carefully woven quilt of stories. Inside every special dish is a collage of memories.

When I think of spaghetti squash, I am reminded of the strength of our marriage and family. I ponder on our unwavering commitment to each other, to our children- and to our independent lives that are also deeply shared.

The cooked spaghetti squash is shredded.

We are now nearing the end of Greg’s ten years of training to reach his goal of becoming a board certified reconstructive head and neck cancer surgeon. He landed his dream job, which begins this summer. For the preceding decade, the hours have been brutal, the cross-country moves have been multiple, the compensation has been revelatory (to say the least), and the strain on our family has been anything but miniscule. Still, here Greg and I stand, blessed with three children and stronger than ever.


On one of Greg’s usual eighty-hour work weeks, though exhausted, he surprised me by going to the store to buy groceries for the week. We are a hungry family of five, so grocery shopping is no small feat. The fruits of his labor were gorgeous. The grocery bags overflowed with greens, berries, heirloom tomatoes, colorful peppers, crunchy carrots, tart apples and beyond. Even more, I discovered not one, not two, but four spaghetti squash. My husband and I both share a deep fondness for the sweet, hearty winter fruit.

Later that year, my dear friend Sharon shared a spaghetti squash recipe with me. It included two of Greg’s favorite sautéed vegetables: onions and mushrooms. Since the first time I prepared it, the recipe has been altered myriad ways and has taken on a completely new life. Still, the beauty of the original recipe inspired the evolution of a new dish: simple, yet impressive and perfectly suited to our family’s collective taste.

Of course, only Vidalia onions would do for my Georgia boy. The tender cremini mushrooms are bountiful and the dish’s flavor enhanced with aromatic garlic and rosemary. The caramelized vegetables are deglazed with tart lemon juice and fruity, dry white wine. The exterior of the bake boasts a crisp crust, and the interior is soft and subtle. Surprisingly, the decadent dish is healthy as can be and completely dairy and gluten-free.


The preparation is time intensive, but the reward is great and leftovers are (occasionally) bountiful. This dish is perfect for a cozy dinner at home with the family, a luxurious ladies’ lunch or even an elegant dinner party.


I enjoy a large scoop of the squash bake garnished with ample amounts of tender, juicy baby heirloom tomatoes and a scattering of fresh, bright parsley. A rich slice of grilled, pesto drizzled salmon is the perfect accompaniment for a more substantial meal. Or, serve scrumptious salads alongside the squash for a lighter, vegetarian option.

Create your own fond memories of family and friends eating, laughing and sharing around a beautiful tray of delicious, delightful winter squash- cucurbita maxima maximized.


Rosemary, Lemon & Caramelized Onion Spaghetti Squash

  • Servings: 6
  • Difficulty: medium
  • Print

Adapted from Joy of Kosher


1 medium spaghetti squash

2 large Vidalia onions, halved and cut into thin rings

1 pound cremini mushrooms, thinly sliced

1 cup homemade or highest quality store-bought marinara sauce

6 Tablespoons dry white wine, such as pinot grigio

2 Tablespoons lemon juice, fresh squeezed or organic, store-bought

3 Tablespoons olive oil, divided

2 teaspoons garlic, finely minced (measure after chopping)

2 tsp. fresh or dry rosemary, finely chopped (measure after chopping)

salt and pepper, for seasoning

6 egg whites, whisked well

coconut or canola oil cooking spray, to grease the baking dish

optional: fresh, chopped parsley and quartered baby heirloom tomatoes, for garnishing


  1. Preheat the oven to 400•F.
  2. Line a medium-sized baking sheet with aluminum foil or parchment paper.
  3. Spray an 9×9-inch ceramic baking dish with cooking spray.
  4. Slice the spaghetti squash in half lengthwise. Scoop out the seeds in the center of each half.  Drizzle the interior of each squash half with 1 tablespoon of olive oil and season with a generous amount of salt and pepper.
  5. Bake uncovered, for about 40-50 minutes, until the squash is fork tender.
  6. Meanwhile, Sauté the onions over medium heat until golden brown and beginning to caramelized, about ten minutes. (When cooking vegetables, season with salt and pepper in each step. In this case, season when you add the onions to the pan and next when the mushrooms are incorporated, below).
  7. Add the mushrooms and sauté a few minutes more, until the mushrooms and onion are both golden brown and have released all of their liquid. Remember to season.
  8. Add the garlic and rosemary to the pan, stir and continue to cook for two to three more minutes, until the garlic has softened. Take care not to brown the garlic.
  9. Increase the heat to medium-high. Deglaze the pan with the lemon juice and white wine, scraping off any brown bits from the bottom of the pan.
  10. Stir in the marinara sauce and remove the pan from the heat.
  11. When the squash is cooked, allow it to cool. Shred the string-like interior of the squash with a fork and place in a large bowl. Discard the outer skin, as it is (sadly) inedible.
  12. Add the caramelized onion-mushrooms mixture to the bowl containing the squash. Taste the mixture. If it needs seasoning, add salt and pepper.
  13. Then, fold in the whisked egg whites to the bowl. Mix all the ingredients together until the egg whites are no longer visible.
  14. Place the mixture in the greased, 9×9-inch baking dish.
  15. Bake the dish in the preheated oven for about an hour. When done, the top with will be golden brown, and a cheese-like crust will form around the edges.
  16. Allow to cool at room temperature for fifteen minutes. Serve the squash on warm plates with a sprinkle of the parsley and scattering of baby tomatoes, if desired. (2013-2016). Unauthorized use and/or duplication of this material without expressed and written permission from this blog’s author, Shanna Koenigsdorf Ward, and/or owner is strictly and completely prohibited.


34 thoughts on “Rosemary, Lemon & Caramelized Onion Spaghetti Squash Bake

  1. I’ve never eaten spaghetti squash. I haven’t even been able to find it at the supermarkets/markets near me (despite much searching) which is pretty frustrating. Love the idea of baking it in a gorgeous dish like this… cheesy, savoury deliciousness. Even better is the recount of your and Greg’s mutual love of this squash and the milestone celebration coming up! I’m glad that the decade-long slog and increased stress upon your family is finally coming to an end. He deserves every success that comes his way Shanna (and so do you, tireless mama and wife!) xxx

  2. Guess what dish will be cooking here over the coming weekend? Yep, this one – it sounds delicious! Have to also tell you that mushrooms and onions are an absolute favorite in the family 🙂

    1. Anatoli, I am so honored that your family will try (and hopefully love!) the recipe. I hope it becomes a favorite and you make it your own. I’m curious about what fantastic vino you pair with the dish- you’re my go-to wine blog!

      1. Shanna, you are too kind! I think this dish is pretty versatile and will work well with wide range of wines. Somehow it makes me crave a nice lightly buttery California Chardonnay. Or alternatively, a nice Pinot Noir from Oregon should match it quite well. Will see. 🙂

  3. What a delicious recipe! Spaghetti squash is one of my favorites and one is rarely enough, except for just me anyway! I know all about the long hours, hopefully they will be less once ya’ll move and settle into your “permanent” home. Hopefully you’ll be able to enjoy real family dinners with everyone at the table more often. Those are certainly my favorite meals, despite the chaos.

  4. Shanna,this is so tempting, I’ve never eaten spaghetti squash before! In Italy we have some sort of baked pasta with vegetables and meat/fish, but it’s a bit different from this (we call this dish “pasticcio” generally) I would like to try it! Love when you describe your family, in the happy and also during the sad moments. Hugs Cris

  5. Hi Shanna, I have never tried spaghetti squash and it is not available here. From the photo I can tell why it is called spaghetti squash!
    The dish sounds and looks lovely.
    So glad Greg’s training is almost over and you can start getting a ‘return on investment’ and enjoy life together even more.

    1. Hey, Stefan! I did some reading, and if you garden, the spaghetti squash does very well in your part of The Netherlands. And, if you are in Javastraat in Amsterdam, apparently some of the Turkish groceries sell it. I think you will love the spaghetti squash. It is one of those vegetables that is delicious even when simply roasted with olive oil, salt and pepper but also makes a great canvas for recipe development.

  6. I love squash too, but found the spaghetti variety too watery when I first tried it, many years ago. I think I should give it another go using your recipe! I also love your blog format with the lovely large photos – when did that happen? I must have been blind!

  7. I love spaghetti squash but the season is almost over here in France. Might have to wait until next winter to try. Looks delicious though!

  8. Lovely recipe, Shanna. I love the fact that it’s oven baked. My youngest and I love caramelized onions with mushrooms. So, I might add the spaghetti squash next time. It’s kind and helpful of Greg to buy grocery for the week. And, ten years of training is such a long time. I’m glad his training is almost over. Congratulations to Greg for landing his dream job. Best wishes to you and your family.

  9. Your writing is beautiful Shanna ❤ We just opened another pumpkin last night, so ofcourse I need to look within the archives of my pumpkin and squash expert which is you 🙂 I want to make a cake! I never thought to make spaghetti with it! Lots of hugs to you and keep looking well after your wonderful family xx

  10. Hello dear Shanna, So good read that your marriage is stronger than ever and as for Gregg’s residency/fellowship is coming to an end and now you both can reap the benefits. Do you know where you would be settling next? xoxo

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