Skewer each pineapple then brush with butter and sprinkle with brown sugar. Grill until caramelized. Set aside.
Top each grilled pineapple with a scoop of ice cream then drizzle with caramel sauce. Sprinkle peanut brittle on top.
Caramel Sauce: In a saucepan, combine sugar and corn syrup and cook over medium heat until sugar turns amber. Slowly stir in cream. Mix well. Turn off heat then add butter. Mix and let cool. Transfer to a squeeze bottle.