Gather all ingredients and equipment.

Heat butter and oil in a large saute pan over medium heat.  Add onions, salt, pepper, cayenne, and saute for 10 minutes.  Reduce heat to medium-low and cook, stirring occassionally, for 20 more minutes until onions are brown and caramelized.  Allow onions to cool.

Place cream cheese, sour cream, and vegenaise in the bowl of a kitchen aid mixer with paddle attachment, beat until smooth.  Add onions and mix well.  Taste for seasonings.