Cook chana dal and cashewnuts with 1½ cups water in a deep non stick pan till just done. You can even pressure cook them.
Cook jaggery with 1 cup water till it dissolves. Mix rice flour with ¼ cup water to a smooth paste.
Add thin coconut milk to the jaggery water and mix well. Add the rice flour mixture and cook on medium heat, stirring continuously. Add green cardamom powder and cook till the flour gets cooked and the mixture thickens.
Add chana dal and cashewnuts and mix well. Reduce heat and add thick coconut milk. Mix well and switch off heat.Serve warm.