Add the full-fat milk to a wide and heavy-bottomed kadai or pan. Heat the milk on medium heat and stir at intervals to prevent scalding the bottom.
When the milk begins to boil, turn the flame to a low level. A layer of cream (malai) forms on the surface, and a spatula is used to push it towards the sides of the pan to attach it to the rim.
Repeat the procedure of boiling and pushing the layers of the cream to the sides. Stir the middle of the milk periodically to make sure that it does not get stuck on the bottom.
Continue simmering until the milk has been boiled down about one-third of its initial amount and the liquid thickens and loses its original dark yellow or pale cream color.
Combine the sugar and the milk infused with saffron. Stir thoroughly between 2-3 minutes until the sugar dissolves completely.
You can now remove all the layers of cream you have scraped off using the spatula on the sides of the pan to the thick milk again. These are the lachhas or the flakes that make rabdi its flavor.
Add 1/2 of the chopped nuts and cardamom powder. Stir it lightly and turn off the heat. The cooling of the rabdi will also increase in thickness. Serve warm or chilled.