In a large saucepan, with the stove turned OFF, add the water then gently sprinkle the gelatin powder over the surface of the water so it coats evenly. Do this one spoonful at a time until all 4 tbsp have been sprinkled over. The water will start to absorb into the gelatin granules, this is called "blooming" and makes dissolving the gelatin much easier than by stirring into hot water. Leave it for a couple of minutes.
A saucepan with a large diameter works best for this so as much gelatin as possible can be exposed to the surface of the water.
When you see the gelatin powder has all become slightly translucent turn the stove onto medium heat to slowly warm the liquid up. Grab a whisk and start stirring as soon as the water has warmed through. Whisk until gelatin granules have completely dissolved.
Remove the saucepan from the stove then add the banana pieces and cinnamon powder then use a stick blender to blend until the mixture looks like a banana smoothie - it should be quite thick. You can leave chunks of banana in there or blend it until smooth, it's up to you.
If you don't have a stick blender simply pour the gelatin water into a regular blender then add the banana and cinnamon to blend thoroughly.
Pour the mixture into either individual serving cups or one large container to then refrigerate. It should only take a couple of hours to set in the fridge. If you use a large container you can slice the set jelly to serve individual pieces on a plate or in a bowl.
Notes
The jelly will turn brown in the fridge. That can’t be helped with banana but it doesn’t affect the flavour at all. Gelatin acts as a natural preservative but is made from beef hide so it will ‘go off’ at some point. The jelly usually lasts about a week in the fridge if sealed with a lid (otherwise it dries out easily) and will start to smell sour when it’s turning. If the jelly is too firm for your liking, simply use a little less gelatin powder next time. If the water jelly layer on the bottom is too thick, use a little less water next time. You just need enough water for the gelatin powder to bloom/soften on, too much will great a separate layer of banana water jelly that will sit on the bottom. Add raw honey or pure Grade B maple syrup into the mixture, or drizzle on when serving. Add nutmeg powder to the mixture. Drizzle some pure coconut milk on top to serve and/or a spoonful of organic desiccated coconut for added flavour, texture and healthy fats. Sprinkle some fresh or thawed organic frozen berries on top to serve, for an added nutrient boost, flavour and texture. Add other fruits, such as mango, that go well with banana.