Bring lightly salted water to boil in a pot. Stir oats into boiling water and reduce heat to medium-low. Cook and stir until oats soften and water is absorbed, about 15 minutes. Remove from heat and allow to cool, about 15 minutes.
Blend oats, cashew milk, and banana in a blender until smooth.
Spoon oat mixture into 2 bowls; top each with diced mango, coconut flakes, and honey.