Combine flour, baking powder, and salt in a bowl. Mash bananas, sugar, vanilla extract, and cinnamon together in a separate bowl. Stir flour mixture into banana mixture until batter is well mixed.

Heat 2 inches of oil in a heavy pot over medium heat. Drop batter by to tablespoon into to oil; cook until lightly golden brown, 2 to 3 minutes per side. Transfer banana balls to a paper towel-lined plate to drain and cool slightly. Dust banana balls with confectioners' sugar.