For the syrup: Combine the sugar and water in a saucepan over medium-high heat, stirring occasionally, until the mixture starts to simmer and the sugar is completely dissolved. Stir in the sage and cook for 30 more seconds. Then, remove the saucepan from the heat and set it aside to cool. Once the simple syrup has cooled to room temperature, remove and discard the sage. Transfer the simple syrup to a clean re-sealable container and store it in your refrigerator until you are ready to use it.

For the cocktails: For a single cocktail, vigorously shake 6 tablespoons (3 ounces) of grapefruit juice, 3 tablespoons (1½ ounces) of the sage simple syrup and 2 to 3 dashes of bitters in a shaker with ice. Strain into a glass with fresh ice. Top with about ½ cup of champagne and garnish with fresh sage leaves, if desired. Serve immediately.

Note: If you don’t have a cocktail shaker, you can use a jar and strain the mixture using a fine mesh strainer.