For the dressing: Combine the mayonnaise, buttermilk, chives, parsley, salt, pepper and garlic powder in a medium bowl and mix well. Refrigerate until ready to serve.
For the burgers: Preheat an outdoor grill to medium-high heat.
In a bowl, combine the beef, Worcestershire sauce, egg, salt and pepper. Shape into 4 patties.
Grill the patties for about 5 minutes per side for medium doneness.
Place each patty on a bun and top with bacon, tomato, lettuce and a generous dollop of dressing. Close the burgers with the top bun half and serve immediately.