Clean, wash and soak the moong dal for 6 to 7 hours. Soak saffron in 1/4th cup of warm milk. Keep it aside. Drain and blend it in a blender to a coarse paste without water.
In a heavy bottom pan or kadhai, add ghee and moong dal paste, mix. Cook on a low heat till the dal turns light golden brown. Stir intermittently.
Once the dal turns golden brown, add 4 cups of milk and mix well. Cook on low heat till 3/4th of the milk quantity dries up. Keep stirring intermittently. Add cardamom powder, sugar, saffron milk, chopped cashew and almonds. Combine well
Start bhuno-fying (cook on a low heat), stirring continuously throughout till the halwa takes a beautiful dark brown color and releases all the ghee flowing in the pan.
Dish out in a serving bowl, garnish with chopped almonds, petals, saffron and warm.
Serve warm. This halwa can be prepared in bulk and stored in an clean and dry airtight container easily upto 3 weeks in refrigerator. You just have to reheat the required serving portion and enjoy anytime.