Place the frozen cherries, crushed ice, mint leaves, lime juice, rum, and simple syrup in a blender. Blend until smooth.
Pour the mixture into chilled glasses and top with crushed ice. Garnish with lime wedges and cherries.
For the lime simple syrup:
In a small saucepan, combine the sugar, water, and lime zest over medium heat. Bring to a boil, reduce heat, and simmer for 5 mins, stirring occasionally, until the sugar has dissolved. Remove the pan from the heat and allow the syrup to cool for 20 mins. Strain before using.