Wrap the squash half in microwave-safe plastic wrap and microwave it, cut side up, at high power (100%) for 10 to 12 minutes, or until it feels soft when pressed. Let the squash stand for 5 minutes. In dutch oven, saute onion, garlic and mushrooms until onion is tender. Add basil, oregano, cayenne salt, pepper and parsley. Saute for another 5 minutes. Reduce heat and stir in sour cream. Discard the squash seeds, scrape the flesh with a fork into a bowl, and toss it with the mushroom mixture. Serve with parmesan.