Soak sago in water for 1 hour.
Bring it to boil and cook on low flame until it becomes transparent. If needed add some more hot water and cook until the sago is soft and transparent.
When there is very little water left, add hot milk to the payasam and let it boil.
Add in sugar and cardamom powder. Let it boil for 5-10 minutes.
In a separate pan, heat ghee and add cashew nuts.
When they are golden, remove from flame and set aside to cool.
Once the payasam is slightly thick, remove from flame and let it sit for five minutes.
Add the roasted cashew along with ghee.
Serve it hot or at room temperature.
