Melt the butter in a large skillet over medium-low heat. Add the onions and ½ teaspoon salt and cook, stirring occasionally, until deep golden brown, 30 to 35 minutes. Remove from heat and let cool.
In a medium bowl, mix together the onions, cream cheese, sour cream, chives, ¼ teaspoon salt, and ⅛ teaspoon pepper. Serve with the chips.