1/3 cup canned cream of coconut (such as Coco López)
1/4 cup fresh lime juice (from 2 limes)
Maraschino cherries, for garnish
Freeze the banana slices on a plate until firm, at least 3 hours or overnight.
Transfer the banana slices to a blender. Add the rum, cream of coconut, lime juice and 3 cups ice. Blend until smooth and thick, adding more ice if needed. Pour into large glasses; garnish each with a cherry.