This Spaghetti Squash Casserole is one of my favorite vegetarian casserole recipes! Healthy and flavorful, it’s naturally gluten-free and so easy to make vegan.
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Spaghetti squash casserole is here to make your vegetarian casserole dreams come true.
I cooke a lot of vegetarian food, and I’ll be honest, casseroles are one of the hardest things to make meatless. This one is special because it combines the heartiness of spaghetti squash with even more veggies and a bit of cheese to create something scoopable and main dish worthy.
This spaghetti squash casserole is a great little detox when you’re regretting eating too many chocolate covered pretzels or light dinner if you’re planning a trip to pilates and don’t want to feel all bloated when you’re trying to sit up without lifting your legs (seriously, try it, it’s impossible… for me).
Spaghetti squash casserole ingredients
- Spaghetti squash
- Olive oil
- Onion
- Mushrooms
- Garlic
- Diced tomatoes
- Salt & pepper
- Oregano
- Thyme
- Mozzarella cheese
- Parsley
How to make spaghetti squash casserole
- Rub the cut side of the squash lightly with olive oil and season with salt and pepper. Place both halves cut side up on a rimmed baking sheet and bake at 400ºF until tender when pierced with a fork, 50-60 minutes.
- Remove from the oven and allow to cool slightly before scraping the insides of the squash with a fork to remove the stringy flesh. Place the squash “noodles” in a large bowl and set aside.
- While you’re waiting for the squash to cool, heat olive oil in a large pan over medium heat. Once hot, add the onions and cook, stirring frequently, until beginning to soften, 3-4 minutes. Add the mushrooms and cook, stirring frequently, 5 minutes more. Add the garlic and cook, stirring, until fragrant, about 1 minute. Season with salt and pepper.
- Add the onion mixture to the squash along with the tomatoes, oregano, and thyme. Stir thoroughly to combine.
- Transfer the mixture to an 8×8 baking dish coated with cooking spray and sprinkle with cheese. Bake 30 minutes or until cheese is melted and it is hot throughout. Garnish with chopped parsley if desired and serve.
Top tips
How to cut a spaghetti squash
I like to cut my squash in half from top to bottom with a big, sharp knife. You can check out It’s a Veg World After All for more tips on how to cut a spaghetti squash. There is no need to cut it any smaller than in half for this recipe.
Drain the tomatoes
Don’t forget to drain the tomatoes of the juice they’re canned in. Adding the extra juice will make the casserole too watery. I like to cut off the lid of the can and then hold it in place while tipping it over the sink to drain the liquid.
Doubling the recipe
This recipe makes six servings, but if you’re making it for a holiday you may want to double it. This is easy to do with the servings slider in the recipe card below.
Tips for customizing spaghetti squash casserole
- Add cooked, shredded chicken for meat eaters
- Leave off the cheese to make it vegan
- Add a diced bell pepper with the onion
- Swap the mushrooms for zucchini, halved and cut into disks
FAQ
While spaghetti squash doesn’t taste exactly like spaghetti, it does have a bland taste that pairs well with other flavors like those you’ll find in this recipe. It tastes similar to other mild squash such as zucchini.
I believe in most things in moderation, but it’s pretty clear that spaghetti squash is more nutritious than ordinary pasta. It’s high in fiber and lower in carbs and calories than pasta. You’ll also get lots of vitamin C, vitamin B6, and betacarotene.
With all those nutritional benefits, there’s no arguing that this is a healthy vegetarian casserole. Just add an easy vegan salad and you have a full meal!
This easy squash casserole is vegetarian, gluten-free, and easily made vegan by leaving off the cheese, making it ideal for serving to guests with a variety of dietary needs. I think it makes a tasty addition to any vegetarian (or, altered, vegan) Thanksgiving spread, and could even serve as the main dish. It would also be a great side dish for meat eaters.
The casserole can get a little watery as the squash bakes the second time, but I don’t mind it because it keeps the squash soft (I hate crunchy squash!). If you don’t like the extra moisture in your squash casserole recipe, simply squeeze and drain the spaghetti squash after shredding it, before adding it to the other ingredients.
More delicious vegetarian recipes
- Vegetarian Stuffing
- Italian Quinoa Casserole
- Crispy Quinoa Bake
- Slow Cooker Vegan Butter Chicken
- Creamy Mushroom Tempeh
- Slow Cooker Quinoa Enchilada Casserole
- Broccoli Quinoa Casserole
- Biscuit Topped Vegetarian Pot Pie
If you make this recipe, be sure to rate it, leave a comment, or tag #theliveinkitchen on Instagram!
Recipe
Spaghetti Squash Casserole
Ingredients
- 1 medium spaghetti squash, halved and seeds removed
- 1 tablespoon olive oil, plus more for rubbing the squash
- 1 medium onion, chopped
- 8 ounces baby portobello mushrooms, sliced
- 1 clove garlic, minced
- Coarse kosher salt and freshly ground black pepper
- 14.5 ounce can diced tomatoes, drained of excess liquid
- ½ teaspoon dried oregano
- ½ teaspoon dried thyme
- ½ cup shredded mozzarella cheese
- Chopped fresh parsley, optional
Instructions
- Preheat the oven to 400ºF. Spray an 8×8 baking dish with cooking spray and set aside.
- Rub the cut side of the squash lightly with olive oil and season with salt and pepper. Place both halves cut side up on a rimmed baking sheet and bake until tender when pierced with a fork, 50-60 minutes. Remove from the oven and allow to cool slightly before scraping the insides of the squash with a fork to remove the stringy flesh. Place the squash “noodles” in a large bowl and set aside.
- While you’re waiting for the squash to cool, heat olive oil in a large pan over medium heat. Once hot, add the onions and cook, stirring frequently, until beginning to soften, 3-4 minutes. Add the mushrooms and cook, stirring frequently, 5 minutes more. Add the garlic and cook, stirring, until fragrant, about 1 minute. Season with salt and pepper.
- Add the onion mixture to the squash along with the tomatoes, oregano, and thyme. Stir thoroughly to combine. Transfer the mixture to the prepared baking dish and sprinkle with cheese. Bake 30 minutes or until cheese is melted and it is hot throughout. Garnish with chopped parsley if desired and serve.
Nicole, RD says
I don’t adore spaghetti squash on its own, but this look FANTASTIC!
Tonia from TheGunnySack says
I love spaghetti squash so I’m going to have to give this a try!
taylor @ greens & chocolate says
I’m on a pretty permanent sugar high as well. I’m trying to keep my meals in between the cookies healthy…this casserole looks perfect for that! Comforting AND healthy!
Rebecca says
About how many servings does this make? It looks awesome.
Maris says
Looks delicious and deceptively healthy!
Lindsay Moe says
Thanks Maris, it totally is!
Cynthia | What A Girl Eats says
We eat a lot of spaghetti squash around here! This sounds perfect for my family!
Lindsay Moe says
Enjoy Cynthia!
Lisa Anne Becker says
I just made this for dinner. It was DELICIOUS!!!! I am new to your site but I will be back again, and again, and again…
Lindsay Moe says
That’s great to hear Lisa, I’m glad you enjoyed it!
Paul says
Lindsay,
Loved the spaghetti squash casserole! Did taste just like spaghetti, and my wife, who’s on Weight Watchers, really appreciated it as well.
Lindsay Moe says
That’s great to hear, glad you enjoyed it!
Pam Allard says
This is one of my go to recipes, thank you! It’s nutritious, delicious and low in calories and carbs.
Lindsay Moe says
I’m so glad you enjoyed it Pam!
Lisa Bixby says
I loved that this was a meatless variation.
I combined the mozzarella with some 6 oz ricotta and made a lasagna style creamy cheesy layer.
Nicole says
Can you freeze leftover casserole?
Lindsay Moe says
Yes, it should freeze well.
Rachel says
I’m a little confused. In step 2, how do you put the squash halves in the oven. I was thinking it was in the baking dish, but later in step 4 it says to transfer the ingredients into the prepared baking dish. So does the squash go directly on the oven racks?
Thank you!
Lindsay Moe says
Thank you for bringing this to my attention! I have updated the recipe to be more clear. You should bake the squash halves on a rimmed baking sheet, the baking dish is for the complete casserole with all the ingredients. Hopefully this helps!
Rachel says
Thank you! Trying this tonight!
Paul Brown says
I have been making Spaghetti squash but after reading this, it seems my way is outdated. I have to try it your way and see what I’ll get.
Paul Brown
Jonna Fletcher says
I made this recipe for dinner tonight and found it to be very bland and non-exciting. There wasn’t a big flavor profile which myself and my family found to be very disappointing.
Jeanne says
Question
Would extra firm tofu work if I added it with the mushrooms?
Lindsay Moe says
Absolutely! Great idea.