3/4 ounce Maker's Mark or other good-quality bourbon
3/4 ounce fresh lemon juice
1/2 ounce fresh orange juice
3/4 ounce simple syrup (see below)
Champagne or other dry sparkling wine, chilled
Lemon twist, for serving
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.