1. Melt butter in large nonstick skillet over medium-high heat and cook chicken, in batches if necessary, stirring occasionally, until chicken is thoroughly cooked. Remove chicken and set aside.
2. Stir sauce and broccoli into same skillet. Bring to a boil over medium-high heat. Reduce heat to low and simmer covered, stirring occasionally, until broccoli is heated through, about 5 minutes. Stir in chicken and cook, stirring occasionally, until heated through, about 2 minutes. Serve over hot fettuccine and sprinkle, if desired, with grated Parmesan cheese.