Cut chicken into 1-inch pieces, and sprinkle with salt and pepper.
Heat oil in a large nonstick skillet over medium-high heat; add chicken, onion, and garlic. SautÃ© 5 minutes, stirring frequently. Stir in broth and tomatoes. Bring mixture to a boil; reduce heat, and cook 5 minutes, stirring occasionally. Add spinach, basil and butter; cook 2 minutes.
Toss chicken mixture with pasta, and top with cheese.