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You won’t miss the dairy when you serve this casserole! The eggs in this recipe create a creamy and “cheesy” crust so divine that you might actually think you put mozzarella right in there.
MORE: Find Tons of Spaghetti Squash Recipes
This recipe can be made ahead and even frozen, it will be your new go to healthy side dish.
Caramelized Onion Spaghetti Squash Casserole
Servings
6 Servings
Ingredients
- 1 medium spaghetti squash
- Extra-virgin olive oil
- Kosher salt
- Freshly cracked black pepper
- 2 medium yellow onions sliced
- 1 8 ounce box mushrooms, sliced
- ½ cup vegetable broth white wine or water
- 1 cup tomato sauce
- 1 teaspoon garlic powder
- 3 eggs whisked
Instructions
- Preheat the oven to 400°F, line a baking sheet with baking paper and grease a 8×8 casserole dish with olive oil.
- Cut spaghetti squash in half lengthwise, scoop out seeds, season with olive oil, salt and pepper and place cut-side down on the prepared baking sheet. Bake for 45 minutes, until the skin of the squash is fork tender.
- While squash is baking, prepare caramelized onions and mushrooms. Heat olive oil in a frying pan over medium-high heat, add onions and mushrooms. Lower the temperature to medium and cook onions and mushrooms until beginning to brown, about 10 minutes, stirring occasionally to prevent burning. Add broth, wine or water to the pan and using a flat edged wooden spoon “scrape” the bottom of the pan to pick up the brown bits. Cook onions and mushrooms for 8-10 minutes more, until there is no more liquid in the pan.
- Remove squash from the oven, scoop out flesh and place in the prepared casserole dish. Stir in caramelized onions, mushrooms, tomato sauce, garlic powder, whisked eggs and season with ½ teaspoon salt and ½ teaspoon pepper. Mix everything together until you can no longer see eggs.
- Bake uncovered at 400°F for 1 hour, until the top of the casserole has formed a golden crust that is brown around the edges. Let rest for 10 minutes before serving.
Video
Nutrition
Nutrition Facts
Caramelized Onion Spaghetti Squash Casserole
Amount per Serving
Calories
116
% Daily Value*
Fat
3
g
5
%
Saturated Fat
1
g
6
%
Trans Fat
0.01
g
Polyunsaturated Fat
1
g
Monounsaturated Fat
1
g
Cholesterol
82
mg
27
%
Sodium
256
mg
11
%
Potassium
505
mg
14
%
Carbohydrates
18
g
6
%
Fiber
4
g
17
%
Sugar
8
g
9
%
Protein
6
g
12
%
Vitamin A
489
IU
10
%
Vitamin C
10
mg
12
%
Calcium
65
mg
7
%
Iron
2
mg
11
%
* Percent Daily Values are based on a 2000 calorie diet.
Preparing this for Pesach 2026. Is the tomato sauce truly necessary? The pic looks like no sauce, and I’d prefer it without. If it is necessary, is there a possible substitute for what the sauce does to the recipe’s composition? OR…. Has anyone omitted the sauce yet? Do tell! Thank you!
It really helps give it that extra flavor, but you can leave it out. It will just be less rich in flavor. If you don’t like tomatoes then it should be fine without.
Hi, the recipe calls for tomato sauce. Does that mean a plain can of tomato sauce or does it refer to the jar of prepared sauce?
Either should work, but I believe it refers to a can of tomato sauce, not with flavors added.
In addition. I could eat that at any time.
A sassy, sexy, yet classy dish. Nothing is missing here to me. Love everything about it. A treat for the eye to see. Got all the perks that men like. Just as fine as it can be. Pure joy! Whoohoo!
Broccoli could work well, you can just leave it out, but if you do use broccoli it would be best if they were lightly sauteed first.
The recipe says tomato sauce, but in the video jamie says marinara. Which is it? And curious why it doesnt look like theres either in the version in the photo. Ty!
Either one works, we use what we can find. The image in the photo does have it, it just doesn’t look like it in the end and with the lighting. Really I doesn’t even taste like it is there but it adds a lot of flavor.
I don’t like mushrooms can I use broccoli instead, and if so should I use it raw
Worked for me ,I cooked my spaghetti squash then scooped it out into freezer bags and froze it. I pulled one out about 2-3 weeks later for a recipe and it was perfect and tasted great 👍
Note : I made sure that I let it cool all the way and drained all liquid from squash before putting in freezer bags .
Great. Thanks for commenting
It should be fine. Will probably continue cooking when you take it out but if it happens that way again you can leave it a little longer at a lower temp so it doesn’t burn but ensures it is done inside.
Thank you!
I just made this. Most of the top is crust like but a few spots look a bit wet. The edges are brown. Is it done?
Oh, I didn’t understand that the issue was avoiding cutting it in half before roasting, but anyways, glad you made it and it worked whole that is good to know.
*Tamar Genger MA, RD | **Executive Editor *
Kosher Network International | JOYofKOSHER.com [email protected]
904.580.7050 ext 250
Hi Tamar. Thanks for your response. I had continued the recipe prior to receiving your answer so I went ahead and roasted the whole spaghetti squash. I then (let it cool a bit) cut it open, took out the seeds and proceeded with the recipe. The dish tasted very good and there didn’t seem to be any issue with roasting it whole. Thanks again!
Only if you can find pre cooked spaghetti squash. You can do it in the microwave too, but you can’t avoid cooking it first to get the strands to come out like spaghetti.
I hope I can avoid cutting it and roasting it whole. Then cutting and scooping before proceeding with the recipe–yes?
You can cook the spaghetti squash in the microwave instead of the oven for step 1 and then just use it in the recipe as stated.
Can you cook the spaghetti squash first in the microwave and then bake it together for the casserole to save time?
usually its 1 tbsp flaxseed to 3 tbsp water to replace 1 egg.
Nevermind! Saw the other comments!
Has anyone tried adding a meat to this?
I calculated 120 calories, 7 grams of fat, 10 grams of carbs, 4 grams of protein. This will vary a bit if you use more than the 2 tablespoons of oil.
Thank you very much!
I am so excited to make this!! Is the nutritional facts for 1 serving? 8 servings per dish? Or the whole dish (haha)? Also, do you know how much fiber is in this? 🙂
Can anyone provide the calorie information?
Thanks so much for letting us know, this is one of our most popular recipes.
Tamar Genger MA, RD
Executive Editor
http://www.joyofkosher.com
http://www.facebook.com/joyofkosher
Twitter @joyofkosher
This exceeded my expectations! The sweetness from the caramelized onions is so good. I guess the part about it tasting cheesy is true, since my dad immediately asked if it had cheese in it when he tried it.
Such great additions thanks for sharing.
Made this last night and I added 2 shredded chicken breasts, used shiitake mushrooms and topped it with olives, it was great! I think it would be super tasty using a homemade enchilada sauce instead of the tomato sauce next time. Thanks! 🙂
It looks amazing!!!! Everyone’s ovens are different so 40 minutes for you can totally make sense.
Really? Thanks! Will eat it tonight and get the verdict.
Made this today. Does this look like the dish you made Melinda? Also it seemed to be done after 40 minutes. Haven’t tasted it yet since we’ll use it for Shabbat.
https://uploads.disquscdn.com/images/aa098dcf672cb8d59161524984f15e91f23a6de479929b6113dc3d35423e019f.jpg
I made this a second time and noticed something I didn’t the first time. The recipe is missing when to add the salt and pepper (listed in the ingredients list). Since ingredients are usually in order of when they are used in the recipe I put them in when I put in the garlic powder. Please update the recipe so that it is correct so other people won’t get confused because salt and pepper are essential seasonings. Also, the second time I made this I used a different tomato sauce. It was better than my first attempt. So, just a note that the tomato sauce you choose is very important in this recipe. It really can transform the dish so choose a good one.
An interesting variation to kugel. I actually liked it best the next day after the flavors melded together some. Also, to my surprise, I actually preferred it at room temperature.
I think chicken breast would be a great addition!! I would use pre-cooked shredded chicken breast for this.
Have you tried making this dish with chicken (or any type of meat in it)? Was thinking about adding chicken breast to this recipe, but trying to decide the best way to cook it. Let me know if you have any suggestions. Thanks!
I’ve never tried freezing it since spaghetti squash can get watery so I wouldn’t recommend it.
can this be frozen?
I don’t believe so since the spaghetti squash is meant to be used like spaghetti and soaks up the eggs and tomato sauce. I’m curious if anyone has tried it with another type of squash…
Can you use any other squashes as I can’t find spaghetti squash in Jerusalem
Absolutely!
Yup, keep it at 400 the whole time.
Can this be made a day ahead of when you want to serve it?
When the casserole is ready to go into the oven to bake for 1 hour is the oven temperature still set at 400 degrees?
What is the purpose of adding the water to the onions and mushrooms?
Thanks for letting us know about the error, although someone did say it would work well with flaxseeds to replace the eggs, we did correct it.
How much flaxseed to make it vegan?
When you search for Vegan recipes on this site, this recipe shows up… but it has eggs?
I made it last week and it was finished almost instantly. My sometimes veggie-weary 5-year-old asked for seconds and thirds right away. It did turn out redder than the photo but was still incredibly delicious. I used shiitakes instead of creminis but either would be great!
Vegetarians are pretty savvy about from where they can get protein. Most wouldn’t expect to find it in a casserole or kugel. My vegan friends would substitute flax seeds for the eggs in this recipe anyway. 🙂
If this is for a vegetarian guest, there had better be another dish available for protein content. It’s a large casserole. Three eggs won’t go very far in supplying protein.
can the tomato sauce be left out. it sounds like it would be better without it or with maybe 1/2 cup
I really dislike when the picture of dish looks nothing like the finished product by definition adding a cup of tomato sauce will make it red I knew this when I started making it but it would be nice if you took a picture of actual recipe mine looks nothing like this one
I think so, this type of recipe should adapt well.
Do you think this recipe would be good without the mushrooms? My husband cant stand them.