Mix the custard powder with enough milk from the 500 ml we have measured out, to make a loose mixture without lumps. Set aside
Heat water in a pan and add the china grass. Mix till it dissolves and becomes lighter. No need to dissolve fully, we will be cooking it later.
Remove this to a bowl and set aside
Add rest of the milk to pan on low heat
Add the china grass mixture first
Then, add the butter and condensed milk
Mix frequently keeping the pan on low flame until the butter has fully dissolved
Now add the salt and custard powder mixture to this and stir continuously, maintaining the heat low
When the mixture thickens a bit (see picture below), turn off heat and add the bread slides, roughly torn up
Give everything a good mix and set aside to cool completely
In the meantime, powder the nuts coarsely and set aside
When the milk mixture has fully cooled, blend to a smooth paste. It will be thick when you transfer to the blender but will become pouring consistency after blending
Pour into a tray greased with butter
Garnish with the powdered nuts generously, forming an even layer on top of the pudding
Cover and refrigerate for about 4 hours
Cut and serve chilled with more powdered nuts on top if desired