Add ½ cup basmati rice to a medium saucepan. Fill the pot halfway with water and swish and lightly scrub the rice with your fingers to release the excess starch in the rice. Drain the cloudy water and repeat this process until the water is fairly clear, then drain once more.
Add ⅛ teaspoon sea salt and 2 cups water to the saucepan on medium heat. Once the water begins to boil, lower the heat to medium-low and simmer for 15-20 minutes or until the rice is cooked through and slightly mushy and most of the water has evaporated.
Add 1 12oz can evaporated milk, ¼ cup sugar, and ¼ teaspoon cardamom Powder to the saucepan and mix. Use the back of your spoon to lightly mash the rice with the milk. Simmer the milk on medium-low heat for 5-7 minutes, making sure to continuously stir, until the sugar is dissolved and the payasam is your desired thickness. Simmer for a longer period time for a thicker and creamier payasam.
Make the Topping: Towards the end of the cook time for the payasam,make the topping in another small saucepan. Add 3 tablespoon ghee to the saucepan and toast 2 tablespoons raisins and 2 tablespoons chopped nuts of your choice in the ghee. Roast for 2-3 minutes or until the raisins plump up and the nuts have a light brown color to them.
Spoon the ghee, nut, and raisin mixture on top of the payasam and serve warm.