Preheat oven to 400°F (204°C).
Microwave the spaghetti squash for 5 minutes, to soften and make it easier to cut.
Cut in half and remove all seeds. Spray with spray oil and then add salt and ground cinnamon amongst two halves. Flip over so the cut side is down and roast for 30 minutes.
Meanwhile, prepare the pumpkin bolognese. In a large pan sauté the celery, onion, garlic, and carrot in the olive oil for 5 to 7 minutes over medium heat. Sauté until fragrant.
Add in the plant boss crumbles, nondairy milk, pumpkin purée, tomato sauce, and nutritional yeast. Continue to cook over medium heat for 5 to 8 minutes and add in water if it looks like it is getting dry. Taste and add any additional seasonings you like.
Once the spaghetti squash is done allow it to cool for a few minutes until it is safe to handle. Then use a fork to shred it and make the spaghetti texture.
Add it into the pan with the pumpkin bolognese and mix until well combined. Add back into the spaghetti squash skins. Cover with vegan mozzarella. Place foil over top and bake for 10 minutes.
Remove the foil and bake for another 5 to 7 minutes until cheese is melted to your preference.
Add sea salt and fresh thyme if desired, and enjoy.