How can you go wrong with onions carmelized in lots of butter? Add to a creamy base and yum yum. This version is by no means low-cal, but it's lightened up with the addition of non-fat Greek yogurt in place of the sour cream. —mamariz
Quarter and slice onions thinly. Melt butter in large saute pan over medium heat. Add onions, sprinkle with sugar if using, and saute stirring occasionally until onions are soft and golden brown. Set aside.
Beat yogurt, cream cheese and cayenne pepper with electric mixer until soft and fluffy.
Fold in onions and season to taste with salt and pepper. Chill until ready to serve.