Spaghetti Squash Gratin

Spaghetti squash has become a vegetable I love to eat when, prior to trying keto recipes, I was certain I would hate it.  When roasted correctly it is tender and slightly sweet and a great base for a multitude of different flavors.  It’s a wonderful low carb pasta replacement and even makes a great breakfast dish, too.  Today’s gratin would be a wonderful holiday side dish or even a light weeknight meal.  I love how easy it was to put together; the hardest part was waiting for the dish to cook as the aroma of garlic, onions and cheese filled my apartment.

I started by pre-heating my oven to 400°F and gathering all the ingredients shown above.  For this recipe I used two small squashes because they looked the best at the store; you can use one large squash, instead, too.

I stood each squash up on its end, took a large non-serrated knife and sliced through each squash top to bottom.  I then used a spoon to scoop out the seeds and other pieces of flesh in the center of the squash pictured in the background of the above photo.  When everything is removed, your squash should look like the two halves in the foreground.

Next I drizzled olive oil over all four halves and generously seasoned them with salt and pepper.  I flipped the halves over so the cut-side was face down on the baking sheet and roasted them for 40 minutes until they were tender.  I removed them from the oven, flipped them back over so they could cool and let them rest for 20 minutes until they could be handled easily.

While the squash cooled, I diced the yellow onion into small pieces.

I also stacked several layers of baby spinach leaves on top of one another and then roughly chopped them into strips.  You don’t want to add whole leaves into this dish but you still want them to be substantial when it has finished cooking.

I added 1 tablespoon of olive oil to a pan and sauteed the onions and garlic over low heat until slightly translucent.  I added the spinach and tossed everything together for about 30 seconds before removing it from the heat.  I did not want the spinach to cook down too much at this point.

After the squash cooled, I used a fork to pull out the spaghetti strands from each half.  They will pull away easily from the skin since the squash is so tender after roasting.

To the squash I added the spinach and onions as well as the sour cream, egg and 1/4 cup of shredded parmesan cheese.  I mixed all the ingredients together in a large mixing bowl until thoroughly combined.

I sprayed an 8×8 glass baking dish with non-stick spray and poured the spaghetti squash evenly in the dish.  I topped with the remaining 1/4 cup of shredded parmesan and baked it for another 30 minutes in the oven.  The squash is extremely tender, slightly cheesy and has a bit of crunch still from the onions.  The sour cream and egg holds the gratin together wonderfully and the bright green spinach is a wonderful complement to the squash.  This dish is best served immediately from the oven, although I have re-heated it the next day in the microwave as well.  What do you love to eat with spaghetti squash?  Let me know in the comments!

Spaghetti Squash Gratin

Prep Time: 30 minutes

Cook Time: 1 hour, 10 minutes

Total Time: 1 hour, 40 minutes

Yield: 6

Serving Size: 1

Spaghetti Squash Gratin


  • 6 cups spaghetti squash, cooked
  • 2 cups baby spinach, chopped
  • 1/2c yellow onion, diced
  • 1tblsp chopped garlic
  • 3tblsp extra virgin olive oil
  • 1/2c sour cream
  • 1 egg
  • 1/2c shredded parmesan cheese
  • Salt
  • Pepper


  1. Pre-heat the oven to 400°F.
  2. Slice the spaghetti squash lengthwise and scoop out the seeds and center flesh.
  3. Drizzle with olive oil, salt and pepper and place cut-side down on the baking sheet.
  4. Roast for 40 minutes until tender. Flip each half so the cut-side is face up and let rest 15-20 minutes to cool.
  5. Dice the yellow onion and roughly chop the baby spinach.
  6. Add 1 tablespoon olive oil to a pan over low heat. Saute the onions and garlic until translucent, add the spinach and stir for approximately 30 seconds until it starts to wilt.
  7. Using a fork, scrape the spaghetti squash away from the skin into small strands.
  8. Add the spinach and onion mixture, egg, sour cream and 1/4 cup of parmesan cheese. Stir until fully combined.
  9. Spray an 8x8 glass baking dish with non-stick spray and add the spaghetti squash.
  10. Top with remaining 1/4 cup of parmesan cheese and bake an additional 30 minutes until golden brown on top.

Nutrtional Information

Per serving: 186 calories, 12g total carbs, 9g net carbs, 13g fat, 5g protein (Note: Please remember these numbers are based on the brands I used and may vary slightly with other brands.)

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  1. Mari Ann

    This looks very good. I think I will try it. Love reading your posts on Sunday afternoons. I look forward to it every week!

  2. JoAnn

    Oh Alison! This looks and sounds incredible. I love spaghetti squash AND spinach.
    Can’t wait to give this a try!

  3. Tammy

    I made this last night, it was very tasty, and I will make it again with a few adjustments. I did find the directions to be a little confusing (I consider myself an experienced cook), and I topped the spaghetti squash with the sour cream mixture instead of mixing in, but it was super delicious anyway. If you read instructions #8 and #9, it never actually tells you to mix everything together. Was it supposed to be mixed? No amount of times reading the recipe made it clear.

    • Hi Tammy, glad you enjoyed it. If you look at the step-by-step photos you can see the sour cream was added into the dish with everything else. #8 on the recipe says “Stir until fully combined.”

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