Fill a large pot with lightly salted water and bring to a rolling boil. Cook fettuccine at a boil until tender yet firm to the bite, about 8 minutes. Drain.

Heat large nonstick skillet sprayed with cooking spray on medium-high heat. Add chicken; cook, stirring occasionally, until chicken is done, 5 to 7 minutes. Remove from the skillet.

Mix broth and flour into the same skillet. Stir in Neufchâtel cheese, 2 tablespoons Parmesan, garlic powder, and pepper; cook, whisking constantly, until mixture boils and thickens, about 2 minutes. Stir in chicken.