Add the cranberries, sugar, water, rosemary, and orange zest to a saucepan.
Bring to a simmer, cook until cranberries burst, and set aside to cool.
Add the cooled cranberry syrup and orange juice to a cocktail shaker filled with ice and shake until frosted.
Pour the cranberry orange syrup into a cocktail glass along with the gin & sparkling water.
Add garnishes like dried orange slices, sugared cranberries, and serve!