Set the oven to Broil. Slice the grapefruit in half. Then, with a small a small knife, slice around the inside of the rind, being careful not to puncture the skin of the grapefruit. Then slice the segments of the grapefruit. Add a sprinkling of brown sugar to the grapefruit and place under the broiler until sugar is melted and grapefruit starts to puff. Serve immediately.