Don’t judge this rich dish by how it looks (somewhat mushy) or tastes (not exactly sumptuous) immediately after cooking. You will be rewarded for your patience if you wait until the dessert has been refrigerated for several hours.
Bring the milk to a near a boil in a heavy-bottomed pan. Decrease the heat to medium-low and let the milk bubble--but not bubble over. Whenever a creamy crust forms at the top, simply mix it into the milk. Stir the milk occasionally until it thickens to about one-fourth of its original quantity and turns light brown in color, about 2 hours. (It will look a little curdled.) Turn off the heat.
Add the sugar and cardamom. Stir until the sugar is completely dissolved.
Lightly heat the ghee in a skillet over medium heat and fry the cashews and pistachios until they turn golden brown, about 2 minutes. Place the nuts on a paper napkin until the ghee is absorbed. Add the nuts to the reduced milk and allow the mixture to cool completely, about 1 hour, stirring occasionally. Transfer into a serving bowl and garnish with saffron. Cover and refrigerate at least 2 hours. Serve chilled.