Soak the rice overnight in water to cover by 2 inches. Drain and place in a blender (not a food processor) along with 1 cup milk and blend, about 1 minute. The mixture will still appear grainy. Reserve. In a small bowl, soak the saffron threads in ¼ cup milk about 30 minutes. Meanwhile, prepare the dessert masala.
Place ½ gallon milk in a large, heavy wok or sauce¬pan and bring to a boil over high heat. Reduce the heat to medium and simmer, stirring and scraping the bottom and sides of the wok often, until the milk has slightly thickened, 5 to 7 minutes.
Add the blended rice to the simmering milk in a slow, steady stream, stirring constantly to prevent the formation steady stream, lumps. (If any lumps develop, let it cool and mix again in the blender until smooth. Then return everything to the pan.) Increase the heat to medium-high and cook, stirring and scraping the bottom and sides of the wok constantly, until the custard is thick and creamy, about 5 minutes.
Add the sugar and cardamom seeds; reduce the heat to low, and cook another 5 minutes to blend the flavors. Remove from the heat, add the rose essence, and bring to room temperature, either uncovered (stir often to prevent a skin from forming) or covered with plastic wrap. Transfer to a serving dish and garnish with silver leaves and dessert masala. Sprinkle with the saffron threads and pour the saffron-infused milk over the top. Refrigerate at least 4 hours and serve chilled.