Heat oil in a large skillet over medium high heat. Saute chicken breasts for 4 to 5 minutes each side, or until white. Add pepper, garlic, onion and broth. Cover and simmer over medium heat until broth cooks off, about 7 to 10 minutes.
Stir in spaghetti sauce, then cover and simmer another 10 minutes, or until chicken is cooked through and no longer pink inside. Sprinkle cheese on top, cover and cook for another 2 to 3 minutes, or until cheese is melted. Serve hot.
