Make the syrup. Simmer the sugar, water, rosemary and clementine peel for 3 minutes, then take off the heat and leave to infuse 30 minutes. Strain and chill.

Make the sugared sprigs. Brush each rosemary sprig lightly with egg white, dip in caster sugar to coat, and leave on paper for 30 minutes to set hard.

Chill six flutes in the freezer for 10 minutes so the fizz stays lively.

Add 2 teaspoons of rosemary syrup and 50ml of cold clementine juice to each glass and swirl once.

Top slowly with prosecco, pouring down the inside of the glass and letting the foam settle before topping up.

Lay a sugared rosemary sprig across each glass and serve at once.