In a cocktail shaker, combine grapefruit juice, rosemary simple syrup* and CBD oil with ice. Shake vigorously together.
*To make rosemary simple syrup, combine 1 part sugar with 1 part boiling water and 5 large pieces of rosemary. Simmer for 10 minutes so flavor permeates.
In a coupe glass, divide the cbd juice from the shake in half between both glasses.
Top with sparkling water.
Garnish with a grapefruit twist