Vegetarian Spaghetti Squash Casserole

This Spaghetti Squash Casserole channels all the flavor of our favorite lasagna recipe with a healthy low-carb twist! This gluten-free recipe can be served as a side dish or a main entree for dinner. Enjoy!

Spaghetti Squash Casserole

You guys, it’s happening.

Fall recipes are on the horizon and I’m pretty much running around in circles squealing with excitement over that I have in store for this veggie-flecked blog of mine.

I have a few tasty t-rex dishes lined up for my omnivores and a whooooooole lot of vegetarian and vegan goodness coming up for everyone else. Have a request for something in particular? Leave me a comment and I’ll add it to the rotation for testing and tinkering!

It’s still very much 5000 degrees here in Florida currently but with a string of dark and stormy weather, I’m diving face-first into comfort food. This family-friendly cheesy vegetarian spaghetti squash casserole is ready to be dished up on repeat – WOOT!

Also… could that be more of an obnoxious title? Gah! Save me from myself!

But first, grab a spaghetti squash and meet me in the kitchen!

Vegetarian Spaghetti Squash Casserole

This recipe yields approx. four servings when paired with your favorite side salad, though also yields two large portions if you’re extra hungry! (Basically half a squash apiece) Feeding a crowd? Feel free to double the recipe!

Cheesy Vegetarian Spaghetti Squash Casserole
5 from 5 votes

Vegetarian Spaghetti Squash Casserole

This Spaghetti Squash Casserole channels all the flavor of our favorite lasagna recipe with a healthy low-carb twist! This gluten-free recipe can be served as a side dish or a main entree for dinner. Enjoy!

Course Main Dish
Cuisine American
Keyword Spaghetti Squash Casserole
Prep Time 10 minutes
Cook Time 55 minutes
Total Time 1 hour 5 minutes
Servings 4 servings
Calories 390 kcal
Author Jenn Laughlin – Peas and Crayons


  • 1 large spaghetti squash (approx. 3 lbs)
  • 1-2 tsp olive oil 
  • 1/2 cup onion
  • 1-2 cloves garlic, smashed and minced
  • 5 oz mushrooms (2 cups chopped)
  • 2-3 oz fresh spinach (1.5 cups chopped)
  • 1 plum tomato, chopped
  • 1.5 cups ricotta cheese
  • 1 egg white (optional)
  • 2/3 cup freshly grated parmesan cheese
  • 1-2 tsp Italian seasoning blend (I love Mrs. Dash)
  • 1/2 tsp dried basil
  • 1/2 tsp garlic powder
  • salt and pepper, to taste
  • 1/2 cup spaghetti sauce
  • 2 oz grated mozzarella
  • 1/4 tsp crushed red pepper flakes
  • 1 TBSP chopped parsley (optional garnish)


  1. Pre-heat oven to 400 degrees F.
  2. Slice your spaghetti squash in half lengthwise and scoop out the seeds. For easy cutting, you can poke a few holes in the squash and microwave it whole for 4-5 minutes to soften it up just a tad. The knife slides through much easier this way!
  3. Rub the cut side of the squash with a teeny bit of olive oil and place on a lipped baking sheet and roast face-down for about 40 minutes, or until tender and easily pierced with a fork. Cooking time will vary a bit depending on the size of your squash so adjust accordingly. Once ready, the once rock-hard exterior of the squash will be visibly softened with a tender interior.
  4. While the squash roasts, prep your cheese and veggies.
  5. Chop your onion, garlic, mushrooms, spinach and tomato, separately, then set aside.
  6. Bring a pan or skillet to medium-high heat with a drizzle of olive oil and sauté onion until tender and slightly golden, then add garlic and mushrooms and continue to cook until softened. Set aside.
  7. In a large bowl, combine ricotta, egg white, freshly grated parmesan cheese, fresh chopped spinach, Italian seasoning, basil, and garlic powder.
  8. Drain your mushroom/onion mixture and add to the bowl along with your chopped tomato. Mix well, adding a little salt and pepper to taste.
  9. Once your squash is ready, allow to cool slightly, then use a fork to separate the squash’s interior into spaghetti-like strands.
  10. Next spritz a baking dish with olive oil and add your forked strands of spaghetti squash, top with cheese and veggie filling and mix.
  11. Add a layer of red sauce and top with mozzarella cheese (as much or as little as your heart desires of each) and an optional pinch of red pepper flakes (skip if sensitive to heat) and bake at 350 F until hot and bubbly, approx. 20-25 minutes.
  12. For golden flecks of mozzarella, switch oven to broil on HIGH for 2 minutes at the end and remove once bubbling.
  13. Garnish with parsley, if desired and serve piping hot with a healthy side salad or roasted veggies for a balanced meal that’s sure to rock your plate! Enjoy!

Recipe Notes

No jumbo squash to be found? You can easily use two 1.5 pound spaghetti squash if needed! The cook times will be exactly the same.

Nutrition Facts
Vegetarian Spaghetti Squash Casserole
Amount Per Serving
Calories 390 Calories from Fat 198
% Daily Value*
Fat 22g34%
Saturated Fat 12g75%
Cholesterol 69mg23%
Sodium 662mg29%
Potassium 754mg22%
Carbohydrates 27g9%
Fiber 5g21%
Sugar 10g11%
Protein 24g48%
Vitamin A 2515IU50%
Vitamin C 15.8mg19%
Calcium 545mg55%
Iron 2.4mg13%
* Percent Daily Values are based on a 2000 calorie diet.

If you get a chance to try this scrumptious Spaghetti Squash Casserole, let me know! You can leave me a comment here (LOVE checking those daily!) or tag @PEASandCRAYONS on Instagram so I can happy dance over your creations.

I can’t wait to see what you whip up!

Roasted Spaghetti Squash Casserole
This Cheesy Vegetarian Spaghetti Squash Casserole channels all the flavor of our favorite Italian lasagna recipe with a healthy low-carb twist! GF

special diets and swaps

  • t-rex chefs: you can 100% add some ground turkey sausage, sliced hot Italian sausage, or shredded chicken to the mix or serve this side-dish style alongside your favorite protein.
  • brontosaurus chefs: serve this alongside a big green salad and you’re good to go!
  • vegan or dairy-free? try my spaghetti squash burrito bowls or add my favorite vegan chili to your roasted spaghetti squash and dive in!

Ready to get super excited?

This casserole method can be used for any of my scrumptious spaghetti squash recipes!

  1. Cheesy Garlic Parmesan Spinach Spaghetti Squash
  2. Cheesy Buffalo Chicken Spaghetti Squash Bowls
  3. Pesto Parmesan Spaghetti Squash with Shrimp
  4. BBQ Chicken Spaghetti Squash
  5. Cheesy Pesto Chicken and Veggie Stuffed Spaghetti Squash
  6. Vegetarian Chili Stuffed Spaghetti Squash
This Spaghetti Squash Casserole channels all the flavor of our favorite lasagna recipe with a healthy low-carb twist! This gluten-free recipe can be served as a side dish or a main entree for dinner. Enjoy!
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Recipe Rating


  • Taryn

    5 stars
    My mom is a vegetarian so I made this when we had them for dinner and everyone loved it.

  • Lily

    Hi Jenn,

    Below on your comment to Mandy, you say the carbs for this are 10g per serve, however in the nutrition info above it says 27g carbs? Is 27g total carbs and 10g are net carbs?
    I am after the net carbs 🙂

    • Hi Lily! The best way to calculate recipes when following a carb monitoring plan is to self-calculate and devise your own serving size based on that. Weighing is important for accuracy as well since spaghetti squash can be 1.5, 3, or even 5 pounds a piece depending on the size you purchase and that will drastically affect the carbohydrates and, in turn, net carbs.

      The general rule of thumb is 7 grams carbohydrates per cup of spaghetti squash and 1.5-2 grams fiber which you would subtract from the squash to net your carbs, I believe. Is that how you’ve been calculating it?

      I allow my recipe card to calculate recipes to give readers an estimate or general idea, but for those following strict nutrition guidelines the best way to go is to self-calculate for accuracy. There are just so many variables and I don’t want to steer anyone in the wrong direction whatsoever. Since my set serving/portion size may be different from others, you could also reduce the serving size to lower carbohydrate intake and add a low carbohydrate side to round out the meal. Hoping this helps some! xoxo

  • Mandy

    5 stars
    I had cooked the squash last night as I had it awhile and didn’t want it to go bad. Looked up online for a recipe and found this. Just finished a big plate full and absolutely LOVE it! I love it better than lasagna and will now be my go-to. Thank you!

  • Dini

    5 stars
    I just ate, but honestly my mouth is watering looking at this! It looks so colorful and flavorful! I’m always looking for ways to incorporate vegetarian dishes into our meals, and this sounds perfect!

    • Thank you Dini! Hope you get a chance to try it!

  • Ivory

    5 stars
    THS dish looks amazing, and it will be put on my must make soon list.

  • Josie

    My husband is a diabetic and a heart patient. Nutrition Facts Per Serving as he needs to what his saturated fat, sodium and carbs

    • Hi Josie! I’d be happy to calculate it with, if you make any changes you will want to just plug in the changes/swaps to ensure better accuracy. I’ll update here once I have the information. xo

      • Hi again! I tried to get a base estimate to get you started! According to per serving this dish has 334 calories, 25 grams of protein, 10 grams carbohydrate, and 11 grams of saturated fat. These results will vary depending on at-home measurements and ingredients.

        Sodium is difficult to calculate just because it depends greatly on the type of spaghetti sauce you use and on the Italian seasoning blend used. I use Ms. Dash sodium-free (love it!) and if you use a very low sodium sauce you should be good to go there! Choosing a sugar-free spaghetti sauce is also a great option if you have one you love or make one at home.

        You can adjust/decrease the saturated fat by adding less cheese and it will still taste great!

        Hope this helps! xo

  • Kelly

    Can this be prepared a day in advance?

    • Yes absolutely! I like to keep the spaghetti squash noodles and filling in seperate containers so I can blot the squash with a paper towel before tossing it together and baking (it gives off a bit of water when it sits, not as much as zucchini does though) but you can have it all combined in the fridge as well if you prefer 🙂

  • 5 stars
    I just love comfort food!! The photos here look so great, makes me wanna try the recipe even more!

  • Such a beautiful pot of deliciousness!!

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