Rinse and dry chicken breasts, salt and pepper. Melt 1 tablespoon butter in non-aluminum skillet over low heat. Add chicken and sprinkle with 1 tablespoon vinegar. Cover and cook over low heat until cooked (3 minutes each side). Remove and keep warm covered with foil. Add 1 tablespoon butter to skillet, add artichoke hearts and saute until warmed. Remove and set aside. Deglaze pan by stirring 1 tablespoon vinegar into skillet. Add chicken broth and simmer, stirring until broth is reduced by 0.5. Add cream, stirring and reduce liquid again by 0.33333333333333. Boil and drain fettuccine and reserve. In saucepan, toss with remaining 4 tablespoons butter. Season to taste. Beat egg yolk in small bowl with 1 tablespoon cold water until foamy, whisk into hot sauce. Remove skillet from heat, whisking constantly. Sauce must not boil after egg is added can add more vinegar to taste. Season as desired. Stir in parsley. Arrange chicken and artichokes on bed of fettuccine. Serve with green salad. Serves 4.