heat the butter in a skillet over high heat. Add the bananas and Brown sugar and cook, turning occasionally, just until the edges of the bananas begin to burn, about four minutes.
Add the rum and stir. Transfer to a blender, add the wafers, ice cream, and milk. Blend until smooth, about 30 seconds. Pour into four glasses each 8 ounces. Garnish each with a dollop of whipped cream. Serves four.