Stir together first 5 ingredients in a large Dutch oven, and let stand at room temperature, stirring occasionally, 2 hours.
Bring pear mixture to a boil over medium-high heat, stirring constantly. Reduce heat to low, and cook, stirring often, 1 hour or until thickened and golden. Cool completely (about 45 minutes).
Trim rind from top of Brie round, leaving a 1/2-inch border on top.
Place Brie round on an ovenproof plate. Spoon 1/2 cup pears over Brie round.