Preheat broiler. Grease glass baking dish; set aside. Cook pasta according to package directions; drain.
In large saucepan, heat oil over medium heat; cook onion, mushrooms, garlic, oregano, salt and pepper for 8 to 10 minutes or until onion is tender and mushrooms are golden brown. Add tomato sauce and bring to simmer; cook for about 5 minutes or until slightly thickened. Stir in basil.
Add pasta and half of the mozzarella to pan; stir to combine. Transfer half of the pasta mixture into prepared baking dish; dollop half of the ricotta over top. Repeat layers. Sprinkle with remaining mozzarella. Broil for 5 minutes or until cheese is melted and browned. Sprinkle with parsley and serve warm.