Mushroom Bolognese Spaghetti Squash Casserole

Spaghetti squash is high in fiber, low in carbs and makes a great substitute for traditional pasta. In this fun vegetarian and gluten-free spin on the classic Italian dish, mushrooms replace the meat, bringing a hearty texture and a great source of essential amino acids and B vitamins. You can also play around with the amount of cheese you use if you have a dairy sensitivity.

Ingredients for servings

    For the mushroom bolognese sauce

  • 2 tbsp olive oil

  • 0.5 large onion finely chopped

  • baby bella (or crimini) mushrooms quartered

  • 5 cloves garlic

  • 2 tsp dried oregano

  • 2 tsp paprika

  • 0.5 tsp red pepper flakes, optional optional

  • 1 teaspoon sea salt

  • 1 can crushed tomatoes undrained

  • 2 tbsp fresh basil chopped

  • For the spaghetti squash casserole

  • 1 large spaghetti squash roasted

  • 1 cup mozzarella cheese grated

  • 0.25 cup Parmesan cheese grated

  • 0.33333333333 cup ricotta cheese


  • 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 sauté pan or pot, heat the olive oil over medium and add the chopped onion.

  • Sauté, stirring frequently, until onion is fragrant and softened, about 8 minutes.

  • Sauté, stirring frequently, until onion is fragrant and softened, about 8 minutes.

  • Add the chopped mushrooms and garlic, and sauté, stirring occasionally, about 3–5 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. Cover and reduce the heat to a simmer.

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

  • Preheat the oven to 400℉ (204℃) and lightly spray or oil a small casserole dish (a 9-inch square or round works well).

  • 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 for 30–45 minutes, until cheese is golden brown and sauce is bubbling.

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

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