Soak the rice in water for about 1 hour. Wash and drain the excess water. Add coconut gratings to the soaked rice and grind it to a coarse paste.
Add 1/2 cup water to the jaggery powder and bring to boil. When jaggery melted completely and started boiling, remove from stove and strain it.
In a thick bottomed vessel, pour 4 cups of water and bring to boil. When it starts boiling, reduce the heat and add the ground rice paste and stir continuously. Allow to cook on low flame till it thickens. Then add jaggery water and stir well. When it blends well add cardamom powder and remove. Cut the coconut into very small bits and fry it in the ghee and add to the payasam.