Place pineapple on BBQ rotisserie, and grill for eight to ten minutes on high heat.
Add butter, brown sugar, and cinnamon to a small saucepan. Place on the grill, and cook until syrupy.
Begin to baste the pineapple with the syrup using a silicone brush, ensuring to coat all sides as it rotates. Continue this process every few minutes, until the pineapple has softened and caramelized.
Carefully remove from grill, and cut into slices. Serve warm with cold vanilla ice cream. Enjoy!