Cook fettuccine according to package directions. Meanwhile, in a large skillet, saute the chicken, onion, garlic, salt and cayenne in butter until chicken is no longer pink. Stir in flour until blended.
Gradually add the half-and-half, peas and cheese. Bring to a boil; cook and stir for 1-2 minutes or until thickened. Drain fettuccine; toss with chicken mixture. Yield: 4 servings.