In a small bowl, combine the gelatine powder and water. Let it sit for a few minutes.
Place it in the microwave and heat for about 20 seconds. Mix well and set aside.
Whip two cups of cream till soft peaks form. This will take about 5-7 minutes.
Add the sugar, and whip on high speed for an additional 2-3 minutes until firm peaks have formed.
Now pour in the mango puree, and gently fold it in until fully combined.
Add a few drops of yellow food color if using and mix well.
Pour the prepared gelatine, and mix well until combined.
Transfer the mango mousse to a serving dish, top with extra whipped cream and chopped mango.
Refrigerate for at least 2 hours or up to overnight. Mango mousse will keep well in the fridge for up to 4-5 days.