Seperatey mix Coco powder with cold milk and then add it to boiling milk and boil the Coco and milk for good 10 min on medium flame.

Now mix custard powder with cold milk and add the mixture into boiling milk and let them boil till it gets thicken.

Now switch off the flame and let it cool down then mix it with hand blender and allow it's to cool in refrigerator for good 4 hours. Then serve it cold with vanilla ice-cream and some chocolate chips.