Cook pasta according to package directions, omitting salt and fat; drain and keep warm.
Heat a large nonstick skillet over medium-high heat; add pancetta. Cook 5 minutes or until almost crisp, stirring occasionally; drain. Add onion, garlic, and mushrooms; cook 4 minutes or until onion is tender, stirring frequently. Add spinach, broth, tomato, and pepper. Cook 2 minutes or until spinach wilts, stirring constantly. Toss with pasta. Divide evenly among 4 bowls. Sprinkle evenly with cheese.