Combine water, sugar, 1 rosemary sprig and cinnamon stick in a small saucepan; squeeze the juices of the blood oranges into the pan and add in the remaining orange peels.

Simmer the mixture over low-medium heat for about 15 minutes, until it reduces by about one half.

Strain the syrup into a glass container, and discard the rosemary sprig, cinnamon stick and orange peels. Chill in the fridge for at least an hour or until ready to use.

Combine 1.5oz of the chilled simple syrup with 1.5 oz of gin in a cocktail glass, top with chilled champagne and garnish with a rosemary sprig and orange peel.