1. Combine the brown sugar and rum and occasionally stir for 10 minutes, allowing the sugar to dissolve and the rum becomes darker.
2. Pour rum syrup over the ham, allowing it to seep into the scored cuts.
3. Optional: sprinkle a dusting of brown sugar over the ham.
4. Place the ham back in the oven on broil at 500°F.
5. Continually baste the ham with the drippings until it is golden brown and the glaze becomes thick syrup.
6. Remove the ham from oven, slice and serve.