Dice onion and add oil to the skillet over medium high heat, add the onions to the skillet, sauté lightly until just softened and then add sugar, mix well and then let continue cooking to caramelize the onions, lower the heat slightly and stir every few minutes, will take about 10 minutes. In a mixing bowl, add cream cheese and the blue cheese, beat until smooth. Add in the Cheddar cheese. Layer the cheese mixture into a baking dish and let chill for 1 hour. Once the onions are caramelized, remove them from the skillet and set aside. Into that skillet add the cranberries, sugar and water, stirring until dissolved. Turn the heat up to medium and wait for the cranberries to pop open and soften, this should take about 6 minutes. Once the mixture has begun to thicken, add in the balsamic vinegar and return the onions to the skillet. Stir well and then let cool. When you?re ready to serve dip, spoon the cranberry mixture on top of the cheese mixture and serve this delicious dip with crackers, ridged potato chips or a veggie tray.