In a medium bowl or jar, combine the rolled oats, coconut milk, chia seeds, maple syrup (if using), vanilla extract, and salt. Stir well until all the ingredients are fully combined.
Gently fold in the diced mango, reserving a few pieces for topping later.
Transfer the mixture into serving jars or dishes, sealing them tightly.
Refrigerate overnight (or at least for 4 hours) to allow the oats to absorb the liquid and soften.
In the morning, give the oats a good stir. If they are too thick, add a splash more coconut milk to reach your desired consistency.
Top the oats with the reserved mango pieces, sprinkle with shredded coconut, and garnish with fresh mint leaves.
Notes
Add more maple syrup for extra sweetness if desired.