First of all, decide whether you want to make one large jelly or small, elegant individual ones. If you are making a big one, line a 1L rectangle cake tin with clingfilm. Put your ripe fruit into your mould or moulds and refrigerate.
Put your gelatine leaves into a bowl with a little cold water to soak for a minute until softened, drain and add the gelatine back to the bowl with the cordial. Place above a pan of water over a medium heat and stir constantly until the gelatine and cordial become a syrup, add your sugar, stir till dissolved, then remove the bowl from the heat and let it sit at room temperature for a minute or so.
Take your fruit and Prosecco out of the fridge. Pour the Prosecco into your cordial mix, and then over your fruit. Some of the fruit might rise to the top, so using your finger, just push the fruit down into the jelly mix so that it is sealed and will then keep well in the fridge. Place back into the fridge for an hour to set.
