Wash the chana dal in running tap water. Drain and dry roast it over medium heat till it begins to turn brown. Keep stirring or else parts of the dal might get more roasted than others or even get burnt.
Once roasted, add enough water to just cover the dal and let it cook for about 10 mins or so. Cook till you can mush the dal in your hand with some considerable pressure. Keep checking for done-ness. You don't want it cooked too much as well.
Drain the dal in a colander and let it stay there for sometime so all the water drains out completely.
Now pat dry the dal with a kitchen towel and pulse it in a food processor till it becomes a crumbly mass, sort of like fine breadcrumbs. You don't want it ground too fine.
Heat the jaggery with ¼ cup of water in a heavy bottomed pan. Once the jaggery is melted, add the ground chana dal to it. It is important to keep stirring while you add it, otherwise you will end up with clumpy dal mass.
Stir well to get the dal added to the jaggery mix. Lower heat, add coconut and ground cardamom and ghee. Turn off heat.
Heat the 1 tbsp ghee in a small pan and add the cashew nuts to it. Once the cashew nuts turn golden brown, add them to the okkarai.
Keep in an airtight container for upto 2 days. If storing for more, keep in the refrigerator.
To warm it, heat a tablespoon of ghee in a heavy bottomed pan /kadhai. Add required okkarai to it. Stir well and serve.