Muddle cranberries, mint leaves, and simple syrup in a cocktail shaker to release juices and oils.
Add bourbon and fresh lemon juice, then fill the shaker with ice.
Shake for about 10 seconds until well chilled.
Strain into a chilled rocks glass filled with fresh ice.
Top with club soda, lime seltzer, or ginger beer.
Garnish with a rosemary sprig and a few cranberries.
Notes
Adjust simple syrup to taste. Use club soda for a lighter sip or ginger beer for a spiced twist. Chilling the glass briefly helps keep the drink crisp.