add the sweetener and water to a pot and bring to a boil. Remove from the heat and stir to dissolve the sweetener. Allow to cool for a few minutes.

Make the drink by adding the frozen mango chunks to a blender along with the rum, lime juice, skinny syrup, salt and mint. Puree until smooth, add the club soda and mix until combined. Pour into a large pitcher filled with ice cubes and garnish each drink with additional mint, if desired.