Cook and drain fettuccine and broccoli as directed on fettuccine package. Toss with 2 tablespoons of the dressing; cover to keep warm.
Meanwhile, in 12-inch nonstick skillet, heat 2 tablespoons of the dressing over medium-high heat. Cook chicken, onion and garlic-pepper blend in dressing 4 to 6 minutes, stirring occasionally, until chicken is no longer pink in center.
Stir roasted peppers and remaining 1/4 cup dressing into chicken mixture. Cook 2 to 3 minutes, stirring occasionally, until warm. Toss chicken mixture with fettuccine and broccoli. Serve with cheese.