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Vegan Spaghetti Squash Casserole with Mushrooms

  • Author: Lizzy
  • Total Time: 1 hour
  • Yield: 6 Servings 1x
  • Diet: Vegan


Creamy, cheesy vegan spaghetti squash casserole with wild mushrooms is the healthy comfort food recipe you've been looking for. 


  • 1 small spaghetti squash
  • 2 tbsp vegan butter or olive oil, divided
  • 1 sweet onion, sliced thinly
  • 2 garlic cloves, minced
  • 1 lb mushrooms of choice, sliced
  • 1 cup cashew or non-dairy milk of choice
  • 2 tbsp gluten free flour
  • 2 tbsp nutritional yeast
  • A few grates of fresh nutmeg, or a pinch of pre-ground nutmeg
  • 1 tbsp fresh thyme, minced well
  • 1 tbsp fresh rosemary, minced well
  • ⅓ cup gluten free breadcrumbs (double if using a larger baking dish)
  • ½ cup shredded vegan parmesan 
  • 1- tsp kosher salt, divided
  • ¼ pepper, plus more for seasoning


  1. Preheat the oven to 375°F. Line a baking sheet with parchment paper. Butter an 8x8 inch baking dish.
  2. Cut the spaghetti squash in half, remove the seeds, and transfer to the prepared baking sheet, cut side down. Roast until fork-tender, 40-50 minutes, turning every 20 minutes. Remove the squash from the oven and let cool until you can handle it.
  3. Increase the oven to 400°F.
  4. Meanwhile, in a large nonstick skillet, heat 1 tbsp butter over medium heat. When hot, add the onion and garlic and sweat until translucent, adjusting the heat as necessary to avoid burning.
  5. Add the mushrooms to the skillet with the onions and cook until the mushrooms release their moisture, 8-10 minutes. Season with salt and pepper. 
  6. Heat the remaining 1 tbsp butter in a small saucepan over medium heat. Add the nut milk and bring to a simmer. Reduce heat to low and add the flour, 1 tbsp at a time, whisking constantly, until thickened.  
  7. Stir in the nutritional yeast, nutmeg, thyme leaves, ½ tsp salt and a pinch of pepper. Remove the sauce from the heat.
  8. Use a fork to separate the spaghetti squash into strands and add to the mushroom mixture along with 3 tbsp of bread crumbs. Stir to fully combine. Mix in the cheese sauce, turning on the heat to loosen it up while you stir. Taste and adjust seasoning with salt and pepper. 
  9. Transfer the vegetables to the prepared baking dish. Sprinkle the remaining breadcrumbs and cheese evenly over the spaghetti squash.
  10. Bake for 8-10 minutes, or until golden on top and heated through. If the cheese isn’t well melted, cover the dish with aluminum foil and bake for 2-3 minutes more. 
  • Prep Time: 50 minutes
  • Cook Time: 10 minutes
  • Category: Dinner
  • Method: Oven
  • Cuisine: American


  • Serving Size:
  • Calories: 178
  • Sugar: 3.7 g
  • Sodium: 425.9 mg
  • Fat: 8.9 g
  • Saturated Fat: 4.7 g
  • Trans Fat: 0 g
  • Carbohydrates: 21.3 g
  • Fiber: 3 g
  • Protein: 4.8 g
  • Cholesterol: 4.4 mg

Keywords: vegan spaghetti squash casserole