Heat butter or ghee in a sauce pan. You will need at least 1 ½ quart saucepan.
When butter is melted, roast cashew nuts and raisins on medium flame until cashews turn brown, raisins puff up and turn brown.
Remove from pan and keep aside.
In the same pan, add vermicelli and roast on medium flame.
Add ½ cup of water, when the pan cools, add 2 ½ cups of milk. Increase the flame to medium high, give a good stir and cook until vermicelli is almost cooked.
Powder cashew nuts, blanched almonds and cardamom to fine powder. Add to vermicelli and stir until it is lump free.
Add sugar and continue to cook until vermicelli is cooked, al dente.
Turn of the flame, garnish with roasted cashews and raisins, and serve hot or cold.
Consistency of vermicelli pudding / kheer / payasam tends to thicken as it cools. If the consistency is too thick, add some milk before serving.