On a plate, mash the bananas, if you prefer, use a blender or food processor to make it easier.
Put the mashed bananas in a pan over medium heat, add the refined sugar and mix very well. Add the packets of jelly powder and start mixing non-stop until the mixture thickens, reduces in volume and starts to release from the pan - this is the ideal cooking point.
Cover the bottom of a bowl or baking dish with a large, thick plastic sheet (make sure the plastic sheet exceeds the edges of the baking dish), add the candy and spread evenly, cover with the extra plastic hanging out of the edges (touching the candy), let it cool until it reaches room temperature.
Then, cut into squares or any other shape you like and finally coat in the granulated sugar. It's ready to eat, serve.