Distribute the strawberries among six glasses and pop them and the Prosecco in the fridge to fully chill.
In a medium pan, add the cordial and sugar over a low to medium heat. Stir to dissolve the sugar and then bring to a boil. Reduce the heat and then leave to simmer for five minutes. Once done, remove from the heat.
In a small bowl cover the gelatin with cold water. Leave for five minutes until the gelatin is completely soft. Remove the leaves and squeeze out as much liquid as possible. Add the gelatin to the elderflower syrup and then whisk until the gelatin has fully dissolved.
Pour the chilled Prosecco into the cordial, briefly stir and then evenly pour over the strawberries in each glass. Pop into the fridge to chill for at least at least two hours, or until set.