To make cashew nut payasam, start by preparing cashew paste. Soak the cashews in water overnight / for few hours. Drain and grind with 1/2 cup of milk into a very fine paste. To shorten the prep time, you could also soak them in water and microwave on HIGH for 3 min. Let them remain in that hot water for 5-10 more minutes. Once cooled, drain and grind nuts with milk as explained above.
Boil the milk on the side in a heavy bottomed saucepan. Once it has come to a boil, add sugar and raisins and let it simmer on a low flame for 8-10 minutes. Add the cashew paste and half the saffron strands. Make sure you keep stirring so that the mixture doesn't stick to the bottom of the pan.
The cashew paste will thicken the milk such that it will lightly coat the back of the ladle. It's time to remove it from the flame.
Garnish with 2-3 strands of saffron and you can either chill it or serve it warm.