Puree the mango and sugar in a blender until smooth.
Transfer to a large bowl and stir in the ricotta and sliced mint.
Spoon 2 tablespoons of the ricotta mixture into each of 3 parfait glasses.
Top with half of the banana slices, and another layer of ricotta.
Top with the remaining banana, and then the remaining ricotta mixture.
Garnish each glass with a sprig of fresh mint. Serve immediately, or chill up to 4 hours.