Add enough oil to coat the bottom of a large skillet and place it over medium heat
Add the onions and cook, stirring frequently, until deeply browned, about 30 minutes
Remove from heat and add the cream cheese, then stir to melt
Scrape the mixture into a large bowl
Add sour cream, mayo, onion powder, bouillon, and Worcestershire sauce, stirring well to combine
Taste and season with lots of pepper and salt if needed
Chill at least 2 hours before serving so the flavors can deepen and the dip can thicken up
