Heat brown sugar and water over medium heat in a saucepan until melted. Reduce to low and simmer 7 minutes or until thickened, stirring often. Remove from heat and cool completely.
Place rum, banana, coconut milk, lime juice and ice in a blender. Blend until creamy. Add more or less ice to reach desired thickness.
Pour into glasses. Swirl in brown sugar syrup and serve with shredded coconut as garnish.