Take the milk in a heavy bottom pan. Turn the heat on medium.
Bring it to a boil. As it starts boiling, reduce the heat to medium-low. Keep stirring and keep cooking till it gets its half quantity. Do stir every five minutes and also scrap the sides and bottom of the pan to avoid scorching the milk.
While simmering the milk, you will see a thin film of malai at the surface. Mix as you stir and it gives grainy texture in the basundi. Now the milk is half quantity, it took me 35 minutes.
Add sugar, cardamom powder, nutmeg, saffron and chopped nuts. Mix and let it simmer for another 5 minutes. Saffron will infuse its color, basundi will be thick, yet runny consistency. Turn off the stove.
This can be served warm, room temperature or chilled.
Stirring frequently: It is very important to stir while it is simmering. In the beginning start with every 5 minutes, as the it starts to thicken stir every 2-3 minutes.
Medium-Low heat: To get the best texture, always simmer on low to medium heat.
Type of pan: Always use wide mouth, thick bottom pan.
Serving chilled: If so then reduce the simmering time by 5 minutes, because as it gets chilled in the refrigerator, it will thicken more.
Double, triple the quantity: Yes, you can. But keep in mind that milk takes more time to thicken, so simmering time will be increased