Mushroom Bolognese Spaghetti Squash Casserole

 Comforting three cheese spaghetti squash casserole with mushroom bolognese sauce – an ultra pleasing gluten-free vegetarian meal. 

Is it safe to discuss cheese yet?

I know many of us are trying to clean up our act in January, but after a solid three weeks, I’m thinking we can loosen up the reigns and rebel just a tad in the form of three magnificent cheeses.  Truthfully, there has been no January cleanse in my neck of the woods.

Three Cheese Mushroom Bolognese Spaghetti Squash Casserole - a comforting vegetarian meal | #glutenfree #recipe #dinner

I’ve been more interested in taking a burrito to go, making laps on the ski hill, and sipping on my après cold beer than cooking…or thinking profound thoughts…or showering… so my cleanse so to speak has been tumbling around in the powder. Mother Nature is such a badass!

Update on 2017 goals? I signed up for this trail half marathon…over 2,000 feet of vert! Because I’m a glutton for punishment. Anyone fancy a light jog? Srsly, though, 13.1 is a long way to go it alone…I’m looking for running partners!

In addition, I found the hip hop class I’m going to join, still haven’t planned a big trip overseas or looked into a silks class, but have been reading at a higher frequency…there’s been some progress! How are your goals coming along?

Fiending for a spaghetti situation? In need of a gooey casserole? Yeeeeeah, this is what we came for, lettuce swan dive into it!

This twice-baked spaghetti squash adventure is probably one of my favorite ways of preparing spaghetti squash. It’s like lasagna, but without noodles.. like a casserole, but on the healthful end of the spectrum.. Like spaghetti bolognese, sans the spaghetti and sans the actual bolognese.

What it is is, is a comforting cheesy Italian-inspired vegetarian meal with a “bolognese” sauce using mushrooms in place of meat. Basically it’s its own animal, and truly, I think you all will love it.

And you guys…it’s

Mushroom Bolognese Spaghetti Squash Casserole - a comforting vegetarian meal | #glutenfree #recipe #dinner

Inspired by the Turkey Bolognese Stuffed Spaghetti Squash I posted a few years ago, this vegetarian version and casserole mash-up is a fun little game changer, and a brilliant make-ahead dinner for your busy workweek. The recipe itself feeds 3 to 4 comfortably – if you need to feed more people, or are a huge fan of leftovers like me, feel free to double the recipe.

I’m going to give it to you straight…this recipe does require a chunk of time investment. It’s not the quickest to prepare, but on the upside, most of the ingredients requires are probably already in your pantry. Plus, this recipe can also be made in parts by roasting the squash and/or preparing the sauce ahead of time.

To cut down some of the work, wanna know what you can do? Omit the sauce-making process by replacing the sauce ingredients with one large jar of your favorite store-bought sauce. You can still make this a mushroom bolognese affair by sauteeing the shrooms in a skillet and adding the store-bought sauce to bring it all together. 


Three Cheese Mushroom Bolognese Spaghetti Squash Casserole - a comforting vegetarian meal | #glutenfree #recipe #dinner

First things first, we’re going to roast our spaghetti squash. For those of you who are new to this endeavor, check out my post on How to Roast a Spaghetti Squash. Once the squash is roasted, we spaghetti it, then place our squash noodles in a casserole dish. Top it with mushroom bolognese sauce (which can easily be prepared while the squash is baking), and three our three cheeses – parmesan, mozzarella, and ricotta. The casserole goes in the oven, and the end result is an ultra gooey, tomato-sauced pile of healthy noodles.

During the baking process, the noodles will become more watery, causing the sauce to be thin at the bottom of the dish. To alleviate this, you can either let the spaghetti squash noodles drain in a collander before using them in the casserole, or allow the casserole to sit for 30ish minutes before serving. Like all casserole/pasta dishes, this meal becomes even tastier the day after you make it, so if you’re willing to wait it out, try preparing it a full day ahead of time!

Three Cheese Mushroom Bolognese Spaghetti Squash Casserole - a comforting vegetarian meal | #glutenfree #recipe #dinner

Course: Main Course
Prep Time: 40 minutes
Cook Time: 1 hour 30 minutes
Total Time: 2 hours 10 minutes
Servings: 4 people



  • 2 tablespoons olive oil
  • 1/2 large onion, finely chopped
  • 8 ounces baby bella mushrooms (or crimini mushrooms), quartered
  • 5 cloves garlic, minced
  • 1 teaspoon rosemary (fresh or dried)
  • 2 teaspoons dried oregano
  • 2 teaspoons paprika
  • 1/2 teaspoon red pepper flakes, optional
  • 1 teaspoon sea salt
  • 1 28-ounce can crushed tomatoes, undrained
  • 2 tablespoons fresh basil, chopped


  • 1 large spaghetti squash, roasted
  • 1-1/2 cups mozzarella cheese, grated
  • 1/4 cup Parmesan cheese, grated see note*
  • 1/3 cup ricotta cheese


  1. Roast the spaghetti squash according to these instructions, or cook the spaghetti squash using your preferred method.

  2. Prepare the mushroom bolognese sauce. In a large saute pan or pot, heat the olive oil over medium and add the chopped onion. Saute, stirring frequently, until onion his very fragrant and has softened, about 8 minutes.

  3. Add the chopped mushrooms and garlic, and saute, stirring occasionally, until very fragrant, about 3 to 5 minutes. Add the garlic, rosemary, oregano, paprika, red pepper flakes, and sea salt and cook another 2 minutes.

  4. Add the crushed tomatoes and bring sauce to a gentle boil. Reduce the heat to a simmer, cover, and cook 30 minutes (or longer to maximize flavor if desired).

  5. Remove the cover and cook at a gentle boil for 10 minutes, until sauce is thick. Add the chopped basil, stir, and set sauce aside until ready to use.

  6. Preheat the oven to 400 degrees F and lightly spray or oil a small casserole dish (9-inch square or round will work great!).

  7. Transfer the cooked spaghetti squash to the prepared casserole dish and sprinkle with sea salt. Pour the mushroom bolognese sauce over the spaghetti squash noodles, then top with the grated mozzarella, parmesan, and ricotta cheeses.

  8. Bake on the center rack of the preheated oven for 30 to 45 minutes, until cheese is golden brown and sauce is bubbling.

  9. Remove from oven and allow casserole to sit 30 minutes before serving.

Recipe Notes

*Omit the parmesan to make this recipe vegetarian. You can replace it with any of your favorite vegetarian (or vegan) cheeses, such as gouda, grueyere, sheep's milk cheese, etc.

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    1. Julia Post author

      Yaaas! The Ricotta-mozzarella-parm trifecta is near impossible to beat! The mushrooms make the sauce soooo tasty! Lemme know if you try it! 😀

  1. Mary

    Well I’m always happy to talk about (eat) cheese – Love the the stuff! This looks simply beautiful!! If I were going to run any type of a marathon – this is what I’d eat!

  2. marcie

    That half marathon sounds like a major feat and I hope you find a running partner! There’s always room for cheese in my diet so I’m loving this gorgeous casserole Julia! Mushrooms and spaghetti squash are favorites of mine so this is looking very good!

  3. Cassidy Stockton

    Dang! That looks so good! I feel like so many folks I know are in the same January funk. Super proud of you for signing up for the half marathon and hip hop class!! I need to jump start my fitness and those are great motivators! Cheering you on from here!

  4. Sarah @ Making Thyme for Health

    That mushroom bolognese sounds so freaking good! I hear you- this is a rough time for any kind of cleanse with it being so cold. All I want to do is curl up with a big bowl of comfort food and cheese is my weakness. 😉

    Have fun training for that half marathon, lol! You’re such an inspiration, lady. 2K feet is no joke!

  5. Traci | Vanilla And Bean

    Sticking to goals, yas, until a cold thwarted me…. but I’m not giving up so easily! I’m still in… and I will say yasss to cheese. This looks scrumptious, Julia and I think just what I need to get my otherwise squash adverse husband to eat squash! Delicious work!

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  9. Schellie

    I made the mushroom bolognese and it was delicious!. My son is a vegetarian but my husband & I are not. We all enjoyed the dish. It is nice to have a go-to website for vegetarian meal options!

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