Roast spaghetti squash 28-32 minutes in 450 degree oven (drizzle with olive oil then fill pan with 1/4 inch of water). Let cool and remove the seeds & pulp and scrape out the long strands of spaghetti.
Heat onion, garlic and mushrooms stirring for 6-8 minutes or until soft
Add tomatoes, season with salt and pepper and cook for 10-12 minutes. Add oregano and remove from heat.
Finish the squash. Melt butter and 3 tbsp. of water in a sauce pan. Add the squash and season with salt and pepper. Cook for 2-4 min or until water is absorbed. Add in half the parmesan cheese and stir.
Use chopped garlic, remaining parmesan as garnish.