In a mixing bowl, whip the heavy cream and 2 tablespoon of powdered sugar until it becomes firm then put in the refrigerator.
In a small bowl, sprinkle the gelatine over warm water and leave it for 10-15 minutes. Then put it into a saucepan over medium heat until completely dissolving.
Now, put the ¾ the amount of mango chunks and granulated sugar into the blender and blend until a creamy mixture forms. Add the gelatine and blend a few seconds more.
Put a tiny layer of the whipped cream in a medium-sized serving bowl, then top it with the remaining mango chunks. Add another layer of the cream, then pour the blended mango mixture over. Put the mousse in the fridge for 2-3 hours.
Use the piping bag to make small blobs of the cream all around the edges, or you can add some chopped mangos on top and enjoy.
Notes
You can replace gelatin with Agar Agar powder (a vegetarian alternative to gelatine that helps to thicken any dessert). You need to put it in room temperature water, not warm until it dissolves. If you add it to warm water, it will lump up.