Preheat oven to 400 degrees. Cut squash in half lengthwise and scoop out seeds. Drizzle with olive oil and season with salt. Place squash cut-side down and roast until tender, about 45-50 minutes. Use a fork to scrape out “spaghetti.”
Preheat a large non-stick skillet over medium heat with the olive oil. Add the onion and cook for 3 - 5 minutes until softened. Add the beef and cook for 5 - 6 minutes until cooked through.
Add the beef broth, oregano, garlic, and canned tomatoes to the pan and simmer for 5 minutes. Add the squash to the meat mixture and heat thoroughly.
Season with salt and pepper and serve with parsley.