In a cocktail shaker or a tall glass, muddle blackberries and rosemary.
2. Step
Add sweetener and ice, shake until well combined. (If you do not have a cocktail shaker, simply pour back and forth between two glasses until combined.)
3. Step
Strain mixture over ice and add ginger beer and a squeeze of lime to taste.
4. Step
Garnish with blackberries and a sprig of rosemary.
