Blackberry Cassis Royale

First make the blackberry purée. Put the blackberries, sugar and the lemon juice into a small pan. Gently cook the blackberries over a low heat until the sugar has melted and the berries start to go soft – approx. 5 minutes.

Purée the blackberries, then push them through a sieve to remove the seeds. Allow the purée to cool. Then mix the purée with the gin and the cassis. Divide this between 4 coupe glasses, then carefully top up with the Prosecco or Champagne. Garnish with some blackberries and a sprig of rosemary.