Place the gelatin into a bowl of cold water and set aside to soak.
Place the cordial, water, sugar and vanilla into a medium saucepan and bring to a simmer. Turn off the heat, squeeze the gelatin leaves to get rid of any excess liquid, and then add to the hot elderflower mixture and stir until the gelatin is dissolved. Set aside to cool slightly.
Wash and thinly slice the peaches and then divide the peaches and raspberries evenly among 6 small (1/2 cup capacity) glasses.
Slowly pour the soda water into the elderflower-gelating mixture, and swirl the pan gently to combine. Divide the mixture between the glasses, and then place into the fridge for at least 4 hours to set. Serve.
Recipe by The Sugar Hit at http://www.thesugarhit.com/2016/01/elderflower-peach-raspberry-jellies.html