1. Preheat oven to 375°F, and line 1 baking sheet with parchment paper. Sprinkle half of sugar on work surface and place puff pastry on top. Sprinkle remaining sugar over dough and use rolling pin to press in.
2. Roll dough to 11-inch square and cut out rounds with 2-inch round cutter. Reroll scraps, and repeat until you have 34 rounds.
3. Place rounds on prepared baking sheet.
4. Place another piece of parchment on top of rounds, and top with another baking sheet.
5. Bake 15 minutes, or until barely golden.
6. Remove top baking sheet and parchment.
7. Bake 5 minutes more, or until cookies are brown and crisp. Cool.
8. Spread chocolate-hazelnut spread on each round, and top with banana slice.