Soften the gelatine sheets in a little cold water for 3 to 5 minutes.
In a medium size saucepan pour in the sugar with approximately 30ml of water and the lemon rind. Heat gently until the sugar has dissolved. Once ready leave to cool and sieve the mixture to discard any lemon rind.
Add the strawberry puree. Squeeze out the excess water from the gelatine and add the gelatine to the mixture.
Mix in the Prosecco.
Place 3 blackberries in the bottom of each champagne glass, carefully pour over enough of the liquid jelly to cover the fruit and chill until set. When the jelly has set pour over the remaining liquid jelly to the top of the glass and refrigerate for 3 hours or until set.
Once ready decorate with the reserved blackberries.