
In a large pot, combine jelly mix, sugar, and 3 cups water. Over medium heat, cook while stirring into a near boil.
Once it starts to boil, remove from heat and pour the jelly liquid into a baking dish. Allow to cool at room temperature and refrigerate for about 1 hour to completely set. Cut into 1-inch cubes.
Peel mangoes and slice the flesh from the pits. Cut the flesh of the five mangoes into cubes and discard the pit and skin.
In a food processor or blender, process the remaining mango into puree consistency.
In a large bowl, combine all-purpose cream, condensed milk, and mango puree. Stir until blended.
Add mango cubes, gelatin, and sago. Gently stir to distribute.
Refrigerate for about 1 to 2 hours to chill. Serve cold.