Heat the broiler and arrange the rack so it's about 6 inches from the heat.
Peel the pineapple, cut it into rounds about 1/2 inch thick, and use a paring knife to cut out the core.
Butter a small baking sheet lightly.
Pat the pineapple slices dry and arrange them on the baking sheet in one layer.
Crumble the brown sugar so it lightly covers the pineapple slices. You can also place the sugar in a mesh strainer and press it through the strainer so it dusts the fruit.
Place the tray under the broiler and cook until the brown sugar melts and caramelizes, about 2 to 5 minutes. Watch it carefully.
Remove it before the sugar burns.
Serve the fruit while still hot.