In a skillet over medium heat, fry bacon until crisp. Remove bacon from skillet and drain on paper towels, then crumble. Set aside.
Add leeks and onions to skillet and cook in about 1 tablespoon of bacon fat until caramelized 10-20 minutes, stirring frequently. Add garlic and cayenne pepper and cook for another minute. When caramelized to your preference, remove from heat and set aside until room temperature.
While the onions caramelize, combine cream cheese, mayo and sour cream in a medium bowl. Stir in sugar and white wine vinegar.
Add crumbled bacon and cooled onions to cream cheese mixture and carefully combine. Season to taste with salt and pepper. Refrigerate for 2-3 hours before serving.
Serve with your favorite chips, crackers and/or vegetables.
Notes
Be sure to clean the leeks carefully as dirt often gets stuck in between the layers. After slicing the leeks, put them in a bowl and run cold water over them to remove any lingering dirt.