Take your “guava sugar-syrup” and add water to it, to make 500 ml of liquid. Make a paste of the 60 ml sugar and custard powder and add this to your syrup. Bring this to a boil on medium heat, stirring all the time until the mixture thickens. Set aside to cool to room temperature. Beat the Evaporated milk till stiff (this will give your desert lift and volume). Add the “guava sugar-syrup” and guavas, fold in. Serve within an hour or two. The “delight” disappear after that and the desert becomes runny.