In a glass baking dish arrange the squash half, cut side down, pour 1/4 cup water around it, and cover the dish tightly with microwave-safe plastic wrap. Microwave the squash at high power (100%) for 12 minutes, or until it is soft when pressed, and let it stand, covered, for 3 minutes. Saute in oil, onions and garlic until onion is transparent. Add tomatoes, basil, oregano, salt and pepper. Simmer for 10 minutes. While the squash is still warm scrape it with a fork to form strands. place strands on plate and pour sauce over. Serve, and pass the parmesan.