Add the butter, sliced red onions, salt, pepper, garlic powder, brown sugar and Worcestershire sauce into a pot and place on a medium heat on the stovetop.
Stir the pot a few times as the butter melts.
Cook the onions down for about 30 minutes until they are softened. Stir occasionally.
Take off of the stovetop, and let the onions cooled completely.
Mix together the mayonnaise, sour cream and fresh chives in a bowl.
Stir in the cooled onions, and refrigerate for 2 hours.
Taste and season if needed, and serve with a sprinkle of fresh chives.