Cut the butternut squash in half length-wise and clean out the seeds.
Brush with oil, season with salt and pepper, and bake uncovered for 40-45 minutes at 180 degrees C.
If the edges start to burn, cover with aluminum foil.
In a pan, saute the garlic and onion in olive oil over medium heat for 3-5 minutes.
Add the mushrooms and cook for 5-7 minutes.
Add the spinach, cook for 30 seconds, then add the flour and cook for an additional 30 seconds.
Add the coconut milk and nutritional yeast, and season with salt and pepper.
Simmer on low, stirring constantly, until it's creamy.
Stuff the baked butternut squash with the mushroom mixture and grate vegan cheese on top.
Notes
Store leftovers in an airtight container in the fridge for up to 3 days and reheat in the oven to keep the top crisp. For a fully vegan dish, use shredded vegan cheese rather than mozzarella.