Add all ingredients to a shaker and dry shake for 15- 20 seconds. Add ice and shake again until well-chilled.
Strain into a chilled coupe or sour glass. Garnish with a sprig of rosemary.
Vanilla Syrup
Combine sugar, water, and vanilla in a small saucepan over medium heat. Bring to a simmer, stirring occasionally, until sugar is dissolved. Remove from heat and cool to room temperature.
Store syrup in an airtight container in the fridge for up to 3 weeks.