Preheat oven to 400°
Coat bottom of 8-inch springform pan with butter. Sprinkle evenly with brown sugar. Overlap slices of banana arranging in concentric circles to cover sugar. Top with puff pastry round, tucking in edges. Place on a rimmed baking sheet and bake until pastry is golden and bubbly, about 20 to 25 minutes. Invert onto plate and serve with ice cream.