Combine the bourbon, lemon juice, orange juice and simple syrup in a cocktail shaker with 6 ice cubes. Shake for 10 seconds before straining into a wine glass and topping with champagne and a lemon twist.
Bring 1 cup sugar and 1 cup water to a boil in a small saucepan over high heat and cook until the sugar is completely melted, a minute or so. Remove from the heat. Transfer to a container with a tight-fitting lid and refrigerate until cold, about 1 hour.