01 - Melt butter in a large skillet over medium heat. Add chopped onions, salt, pepper, and sugar. Cook, stirring frequently, until onions are golden brown and caramelized, approximately 18–20 minutes. Remove from heat and allow to cool completely to room temperature.
02 - In a medium mixing bowl, combine mayonnaise, sour cream, softened cream cheese, Worcestershire sauce, and fresh chives. Whisk until smooth and thoroughly blended, ensuring no lumps remain.
03 - Add the cooled caramelized onions to the creamy mixture. Fold together using a rubber spatula until evenly incorporated. Taste and adjust salt or pepper as needed to reach desired flavor balance.
04 - Cover the bowl tightly with plastic wrap or a lid. Refrigerate for at least 1 hour to allow flavors to develop and meld. The dip can be prepared up to 2 days in advance and stored covered in the refrigerator.
05 - Transfer the chilled onion dip to an attractive serving bowl. Sprinkle with additional freshly chopped chives for garnish. Arrange alongside thick-cut potato chips for dipping. Serve immediately while chips remain crisp.