Combine all ingredients (except sparkling water) with ice in a shaker cup. Shake and fine strain into Collins glass over fresh ice. Top off with sparkling water and garnish with a sprig of rosemary and a few fresh cranberries.
Add sugar and water to a pot and heat on high heat until sugar dissolves. Next, add cranberries, rosemary, and orange zest, and cook on low to medium heat until all cranberries burst open. Remove from heat and strain out the liquid. Allow to cool, then bottle and store in the refrigerator. Yields about 20oz of syrup