Add all ingredients except for Coca Cola and garnish into an ice-filled cocktail shaker. Shake vigorously for 20 seconds. Strain into ice-filled rocks glass. Skewer cherry, rolled up lemon peel, and second cherry with a cocktail pick. Place on top of the glass. Serve.
Combine demerara sugar and water in a small saucepan over medium heat. Stir over heat until sugar is dissolved. Let cool to room temperature before using. Demerara syrup will keep in airtight container the fridge for up to two weeks.