Start by peeling the bananas and cutting them into smaller pieces.
Add the juice of half a lemon all over the bananas.
This process will prevent the bananas from turning brown.
Next, cut the puff pastry into 9 equal squares.
Take one of these squares and make a cut in the middle of each side, without cutting the pastry all the way through.
Add ½ teaspoon of Nutella to the center of the pastry, top it with 1 of the pieces of banana we cut earlier and close by putting the ends together.
Repeat this process with the entire pastry.
Transfer everything to a large baking tray, take it to a preheated oven at 180° C (350° F) and bake for 30 minutes.
Finish by sprinkling powdered sugar to taste over everything.
Serve.