Preheat the oven to 500 degrees . Arrange the papaya halves cut side up in a large baking dish so they support one another and wont tilt or spill. In a measuring cup or small pan with a spout, stir together the brown sugar, rum, lemon juice and pepper until the sugar dissolves. Pour in the glaze to almost fill the papaya cavities. Brush the glaze on all the exposed flesh.
Roast the papayas until tender when pierced with the tip of a knife, about 15 minutes. Transfer to dessert bowls and drizzle with the heavy cream.