Step 1Combine the milk and grated carrots in a heavy-bottomed pot. Bring to a boil. Lower the heat to medium and cook, stirring occasionally, until all the liquid has evaporated, about 1 hour.
Step 2Add the ghee, reduce the heat to medium-low, and cook the carrot-milk mixture, stirring frequently. Keep doing this until the carrots turn reddish brown, 45 minutes to 1 hour.
Step 3Add the sugar (or honey) and, if you like, the cashews and pistachios. Cook the mixture, stirring, for about 5 minutes. Turn off the heat and transfer the pudding to a serving bowl, garnished with cardamom.