Empty the milk into a thick-bottomed pan and add the sugar. Heat gently on a low heat. Add the rice to the milk and let it cook. Stir occasionally to prevent the rice from getting burnt at the bottom of the pan. The rice takes about 15 minutes to cook.
Make sure that the rice is cooked, but not too mushy. Add the condensed milk slowly to the simmering milk. Keep stirring from time to time, until the quantity of the mixture is reduced by about half.
Add the crushed cardamom and garnish with nuts. It can be served hot or cold. The pudding tends to thicken with time. By adding milk, you can adjust the consistency of the pudding.