How to Make It
Cook pasta according to package directions, omitting salt and fat. Drain pasta, and keep warm.
While pasta cooks, heat a large skillet over medium-high heat. Coat pan with cooking spray. Add onion, beef, and garlic; cook 4 minutes, stirring to crumble beef. Add zucchini and mushrooms; cook 10 minutes or until most of liquid evaporates, stirring occasionally. Place tomatoes in a mini food processor; pulse 4 times or until almost smooth. Add tomato paste, oregano, and red pepper to pan; cook 1 minute, stirring frequently. Stir in tomatoes; reduce heat, and simmer 5 minutes or until slightly thickened. Stir in salt and black pepper. Serve sauce over pasta; top with cheese.