Wash the tapioca pearls 1-2 times in water, drain the water. Add the tapioca pearls to a bowl, add 1/2 cup of water and set aside for 2 hours. The tapioca pearls will plump up as they soak. The time of soaking depends on quality of your sabudana, it can take upto 10 hours to soak.Make sure that after soaking, the tapioca pearls are soft and can easily be squeezed between thumb and finger. Drain the water(if any) after soaking. Set aside.
In a heavy bottomed pot, melt the ghee on low. Add the nuts to it and sauté for about 20-25 seconds till you smell the aroma. Take out in a bowl and set aside for garnish.
In the same pot, add the cardamom seeds and slowly pour the milk. Set the stove on medium and let milk come to a boil. Reduce the heat to low and let the milk reduce for 20-25 minutes. You will need to stir and scrape sides in between to make sure that the milk is not sticking to the bottom.
Once the milk is reduced a little, add the soaked tapioca to the pot and mix well.
Cook on low - medium heat for 30-35 minutes with continual stirring till you see that tapioca pearls have started to become translucent and are cooked through. The kheer will thicked and become silk like consistency as you cook it.
Add the saffron milk at this point mix well. Let cook for another 5-10 minutes on low till the tapioca are cooked through. You can pinch one of the pearls between fingers to check that they are soft. When the kheer is thick enough(thicken it more than you think, since condersed milk will thin it out),mix in the condensed milk, simmer for another 5 mins(keep an eye since the kheer gets little sticky) and then take off the stove and let cool down for 10 minutes.
You can mix the ghee sautéed nuts. Serve the kheer warm or cold garnished with more nuts (if desired) .