Add coconut milk and sugar to a saucepan and stir over medium heat until sugar and salt is dissolved. Add the bananas to the pot and cook, stirring often until the bananas are integrated into the mixture. Make a slurry in a separate small bowl by gradually whisking 2 tablespoons water into the cornstarch. Whisk slurry into mixture in pot and allow to reduce and thicken until it is the consistency of yogurt. Transfer to serving dishes and chill.