Start by making the mousse. In a food processor, add your mangos (peeled and diced) and puree them until smooth. set aside
In a medium pot add your coconut milk, whole milk and sugar. Cook on medium heat until sugar is melted and mixture come to a simmer. make sure to continuously stir so that your mixture does not burn.
Once mixture is lightly bubbling remove it from the heat and add your pureed mangos
in a small bowl mix together your cornstarch and water and whisk until combined. Now add this mixture to your milk mixture. Mix until all combined.
Place back on the stove and cook on medium high heat until boiling. Stir continuously so that the mixture does not burn. once it starts boiling, cook until the mixture thickens significantly. this should be about 10- 15 minutes. and again keep stiring .
Once thickened remove from heat and let cool down to room temperature. you can place this in the fridge to speed up the process.
In the bowl of a stand mixer, add your heavy cream and whip on high until you reach soft peeks (looks like whipped cream).
Once your milk mixture is cooled down, whisk it again one more time to smooth it out. Then fold in your whipped cream.
Let your mousse cool in the fridge for at least one hour and it should continue to thicken.