Cook pasta according to package directions, omitting salt and fat.
Meanwhile, warm the olive oil in a large nonstick skillet over medium heat. Add onion and cook, stirring, 4 minutes. Add garlic and cook, stirring, 30 seconds. Add tomatoes and broth; bring to a simmer, and cook 5 minutes or until the tomatoes soften and some liquid evaporates. Use a wooden spoon to lightly crush tomatoes. Slowly stir in spinach or arugula; cook, stirring, 2 minutes or until leaves wilt.
Drain pasta. In serving bowl, toss pasta with warm tomato-spinach sauce. Season with salt and pepper. Garnish with cheese.