Comforting three cheese spaghetti squash casserole with mushroom “Bolognese” sauce – an ultra pleasing gluten-free vegetarian meal.
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 just. so. cheesy.
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.
How to Make Mushroom Bolognese Spaghetti Squash Casserole:
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.
While the squash is roasting in the oven, prepare the mushroom Bolognese sauce. You can also prepare the sauce up to 5 days in advance for an even more flavorful experience, or to break the recipe into parts.
Once the squash is roasted, we spaghetti it, then place our squash noodles in a casserole dish. Top it with mushroom Bolognese sauce 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.
Recipe Tips:
- During the baking process, the spaghetti squash “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 colander before using them in the casserole, or allow the casserole to sit for 30 minutes before serving.
- To cut down some of the work, you can use store-bought sauce. To do so, omit the sauce ingredients with one large jar of your favorite store-bought sauce. You can still make this a mushroom Bolognese affair by sautéing the mushrooms in a skillet and adding the store-bought sauce to bring it all together.
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!
You May Also Love:
- Wild Rice Chicken Casserole
- Tuna Rice Casserole
- Butternut Squash and Bacon Breakfast Casserole
- Spaghetti Squash with Roasted Pecan Pesto
Mushroom thy Bolognese!
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Mushroom Bolognese Spaghetti Squash Casserole
Ingredients
MUSHROOM BOLOGNESE SAUCE
- 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
SPAGHETTI SQUASH CASSEROLE
- 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
Instructions
- Roast the spaghetti squash according to these instructions, or cook the spaghetti squash using your preferred method.
- 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.
- 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.
- 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).
- 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.
- Preheat the oven to 400 degrees F and lightly spray or oil a small casserole dish (9-inch square or round will work great!).
- 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.
- Bake on the center rack of the preheated oven for 30 to 45 minutes, until cheese is golden brown and sauce is bubbling.
- Remove from oven and allow casserole to sit 30 minutes before serving.
Video
Notes
Nutrition
Yummy. I don’t understand how omitting only the Parmesan cheese makes this dish vegetarian. All of the cheeses listed come from animals. Meatless, yes.
Hi Brenda,
Most cheeses are vegetarian (since they’re made from milk and not animal meat). Parmesan cheese is not vegetarian as animal rennet is used in the processing of it. In this sense, the recipe is vegetarian without the parmesan cheese, and can easily be made vegan by swapping all the cheeses for vegan versions. Hope this makes sense! xo
This recipe is one of our favorite go to dinners! It is hearty and healthy. It also refrigerates well if you have leftovers and is just as good the second time around! Thanks.
I’m so happy to hear it, Denise! It’s a fun one, for sure! xoxoxo
I substituted Rao’s bolenese sauce but included sauted mushrooms onions garlic and italian herbs came out great! A keeper recipe
That’s awesome! Happy you like it!
I’m making this for my Sunday dinner! Looking forward to it! — I was just wondering if you know what the calories would be without the dairy? (Mozzarella, Parmesan and Ricotta Cheeses?) Thank you!!
so yummy and since I don’t eaat cheese I made my own Ricotta with cashews and used daiya dairy free cheese no parm and it was still as delicious
Oooh, I’ve been meaning to make dairy-free ricotta! Love it! Thanks for the inspiration! xo
Thank you for sharing this wonderful recipe! I made this yesterday & it was outstanding. It’s an absolute keeper. I think you could also just use the mushroom bolognese with the spaghetti squash, sprinkled with some cheese, & it would be fantastic too. I’ll try that next time.
Thank you again!
Yaaay That’s great to hear, Amy! Thank you for the sweet note! xoxo
This dish is a winner!!! We did add a pich of sugar to cut the acid from the tomatoes. Can’t wait to try other recipes. My husband and I are transitioning to vegetarian. This was a wonderful start….Thank you!
I’m so thrilled to hear it, Kathy! The sugar was a fabulous idea. Many thanks for your sweet message! xo
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!
I’m so happy your family liked it! Thanks for the sweet note! 😀 xo
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!
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!
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!
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!
I mean, I just posted an alfredo sauce, sooo…YES CHEESE! ALL THE CHEESE. Love how comfortful this looks!
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!
Thank ya, Mary! I’m definitely glued to cheese these days!
Wow, Julia! Adding this to my list for next week’s meals. This looks truly delightful!
My 3 favorite cheeses! I cannot wait to try this. Love the idea of a mushroom bolognese for a meatless meal!
Yaaas! The Ricotta-mozzarella-parm trifecta is near impossible to beat! The mushrooms make the sauce soooo tasty! Lemme know if you try it! 😀
Trying this tonight!! Yum! And the photos are just as lovely