Step 1In a measuring cup or bowl, muddle the vanilla, orange zest and rosemary in the sugar. Add the water and stir until the sugar dissolves. Set the syrup aside for a few hours to give the flavors time to infuse. Strain before using. This makes a generous 1/2 cup simple syrup, more than is needed for the remainder of the recipe. The syrup will keep, covered and refrigerated, up to 1 week.
Step 1In a cocktail shaker, combine the rum, cream, simple syrup and bitters over ice. Shake well and strain into an Old Fashioned glass. Add ice, and garnish with grated nutmeg and a flaming rosemary sprig.