Rinse white rice 2-3 times with water and soak it in 1 cup of water for an hour
Drain the water and add the rice to a blender. Blend to make a coarse paste.
Heat ghee in a heavy bottom pot over medium-high heat.
When the ghee is hot and shimmery, add 1 litre of whole milk (full fat milk) to the pot and bring the milk to a boil. Keep stirring the milk throughout cooking to avoid scorching at the bottom of the pan.
Once the milk comes to a boil, reduce the heat to low. Add the coarse rice paste and 1 pinch of saffron strands to the pot and cook until the phirni is reduced (40-45 minutes). Stir frequently.
Once the phirni has reached the desired thickness, add ¼ cup sugar and cook for a minute.
Remove the pan from the heat and cover it with a lid to prevent the formation of a cream layer (malai) on top. Let the phirni cool down to room temperature.
Once cooled, add 1 cup mango puree to it and mix well. Check for sugar and add more if needed. Stir well until the sugar is dissolved.
Transfer mango phirni to small earthen bowls (or normal bowls) and cover with cling wrap. Refrigerate for 5-6 hours. Garnish with slivered pistachios, dried rose petals, and mango cubes, and serve chilled.