Melt the butter in a large skillet over medium heat. Add the onions and cook until they turn a deep golden brown, about 40 minutes, stirring frequently. Add a tablespoon of water to the pan as needed while cooking the onions when they seem dry. Remove the pan from the heat and stir in the Worcestershire sauce. Let the onions cool slightly, about 15 minutes. Transfer the onions to a cutting board and coarsely chop. Set aside 2 tablespoons of the chopped onions.
Mix the sour cream, cream cheese, parsley, onion powder, and beef bouillon in a large bowl until completely smooth. Stir in the onions and season with salt and pepper. Garnish the dip with the reserved chopped onions and parsley and serve it with potato chips.
