Spread the Camembert cheese evenly onto one slice of bread. Spread a thin layer of cranberry sauce over the cheese. Drizzle with a few drops of balsamic vinegar, and top with the remaining slice of bread. Spread butter on the outer sides of each slice of bread.
Heat a skillet over medium heat. Fry the sandwich for a few minutes on each side, just until golden brown. Slice in half, and eat straight away!