- Cut the pineapple into 8 wedges, remove core and rind with a knife.
- Place the wedges into a freezer bag with the brown sugar, seal the bag and massage brown sugar onto the wedges.
- Allow the pineapple to macerate in the brown sugar for anywhere from two hours to two days; refrigerate if macerating more than a few hours. The pineapple should release enough juice to dissolve the brown sugar completely.
- Heat the grill to medium heat.
- Add the vanilla and rum to the bag, seal and shake.
- Remove the pineapple from the bag and place it on the grill.
- When the pineapple becomes caramel colored on the bottom side, rotate it. Repeat for each of the 3 sides of each wedge, then remove from the grill.
- Pour the juice from the bag into a saucepan and reduce over medium heat to a thick syrup (be careful of flare-ups during the first minutes since there will be alcohol from the rum and vanilla extract).
- Serve the pineapple alongside a main dish or serve with ice cream and drizzle with the reduction sauce.