- In a medium skillet over medium-low heat, add the oil. Once the oil is shimmering, add the chopped onions. 
- Cook the onions slowly, stirring occasionally, for 40 to 45 minutes, or until they are deeply caramelized and jammy. Reduce the heat if they begin to brown too quickly. If the pan gets too dry, add a splash of water and stir. 
- Once the onions are caramelized, remove the skillet from heat and let the onions cool to room temperature. 
- In a medium bowl, combine the softened cream cheese, sour cream, Worcestershire sauce, and kosher salt. Whisk or stir until smooth and fully combined. 
- Fold in the cooled caramelized onions and mix until evenly distributed. 
- Cover and refrigerate for at least 1 hour before serving to allow the flavors to blend. 
- Garnish with parsley and serve cold with plain potato chips.