Position rack in center of oven and preheat to 400 degrees.
Line a heavy large cookie sheet with foil. Spray foil with nonstick spray. In a medium bowl combine bananas and syrup. Mash bananas slightly with a fork. On a clean surface, lay flat 1 sheet of puff pastry. Cut pastry in 1/2 lengthwise. Using a rolling pin, roll out each pastry sheet into a 15 by 5-inch rectangle. Cut each rectangle crosswise into thirds, forming 6 squares total. Evenly distribute 1/2 of the banana mixture onto center of each square. Fold corners of pastry into center and pinch ends together, twisting to seal. Repeat with remaining sheet of puff pastry and banana mixture. Arrange pastries on prepared cookie sheet. In a small bowl, combine sugar and cinnamon. Brush pastries with milk. Sprinkle cinnamon-sugar over pastries. Bake for 15 minutes or until golden. Serve warm.