1. In a food processor or mini-chopper, add the butter, chives and parsley. Pulse until well combined and slightly softened.
2. Take each hamburger patty and make a well in the center. Form a ½″ ball of herb butter with your hands and press it into the well. Gently fold over the outer edges of the burger to cover the butter completely and seal it in. Repeat with remaining 3 patties. *At this point uncooked burgers will last, tightly wrapped, in the fridge for up to 6 hours.
3. Set your grill or grill pan at medium heat. Place the hamburger patties on top and cook, turning occasionally, to desired doneness. While the burgers are cooking, place the buns either on the grill or in the toaster. After they have toasted swipe them with a thin layer of remaining herb butter and set aside.
4. Plate burgers on toasted buns and serve hot.