Cook noodles according to package instructions. Drain.
Meanwhile, in a large non-stick wok, heat oils over medium high heat. Cook onion and garlic until softened. Stir in chicken, and cook until chicken browns. Stir in ginger, bok choy, chicken stock, sherry, soy sauce and hoisin sauce.
Toss noodles with chicken mixture until well coated. Serve warm sprinkled with sliced spring onions.