Comforting three cheese spaghetti squash casserole with mushroom “Bolognese” sauce. An ultra pleasing gluten-free vegetarian meal.
This twice-baked spaghetti squash casserole 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. Similar to spaghetti Bolognese, sans the spaghetti and sans the actual Bolognese.
All factors considered, we’re looking at a comforting cheesy Italian-inspired vegetarian meal with a “Bolognese” sauce using mushrooms in place of meat. Basically it’s its own animal, and I truly think you all will love it.
If you’re a meat lover, feel free to add one pound of ground beef, Italian sausage, or ground turkey to the tomato mushroom sauce!
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.
Let’s make a casserole with spaghetti squash!
How to Make 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!
More Casserole Recipes:
- Wild Rice Chicken Casserole
- Tuna Rice Casserole
- Butternut Squash and Bacon Breakfast Casserole
- Spaghetti Squash with Roasted Pecan Pesto
Mushroom thy Bolognese!
Spaghetti Squash Casserole Recipe
Ingredients
Mushroom Bolognese Sauce
- 2 Tbsp olive oil
- 1/2 large onion finely chopped
- 8 ounces baby bella mushrooms or crimini mushrooms, quartered
- 5 cloves garlic minced
- 1 tsp dried rosemary fresh or dried
- 2 tsp dried oregano
- 2 tsp paprika
- 1/2 tsp red pepper flakes optional
- 1 tsp sea salt to taste
- 1 (28-oz) can crushed tomatoes undrained
- 2 Tbsp 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
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It takes a bit of cooking time but it is so good! It takes like lasagna but without the carbs. Will be adding it to my dinner rotation! I was thinking of adding some veggie crumbles next time for more protein.
I love hearing that, Stacie! Thank you for sharing your experience! xo
Can you freeze this dish? Or would you freeze this recipe up to a certain point and then add the cheese when it’s time to bake it?
Hi Laurie! Either option will work 🙂 If it were me, I would probably make the whole recipe and then freeze it, but it’s up to you if you’d rather add the cheese after reheating it 🙂