Melt butter in skillet over medium heat.
Cook onion in butter for 10 minutes, stirring frequently.
Stir in cranberries, brown sugar and vinegar.
Cook about 5 minutes longer, stirring frequently, until mixture is thickened and caramelized.
Heat oven to 350 degrees f.
Lightly brush oven-proof plate with vegetable oil or Pam spray.
Place cheese on plate.
Bake uncovered 8 to 10 minutes or until cheese is soft and partially melted.
Spoon topping over cheese.
Serve with crackers or bread.
