To Create Rosemary Simple Syrup: Steep 2-3 sprigs of rosemary in 1 cup of hot water, like you would a tea, until color has changed and flavor is quite potent. Add 1 cup sugar and stir until dissolved. To Mix Cocktail: Shake first four ingredients together, strain into cocktail glass over ice. Top with ginger beer and garnish with a rosemary sprig. For optimal rosemary flavor, clap the sprig between your hands to release fresh herb oils.