Preheat a grill or grill pan to medium heat. Coat grill grates with cooking spray
In a small bowl, whisk together the brown sugar, butter and cinnamon.
Brush the browns ugar mixture over both sides of each pineapple slice.
Place the pineapple slices on the grill in a single layer. Cook for 2-3 min per side. or until golden brown and tender.
Serve immediately, granished with raspberries and mint if desired.