Infuse the saffron. In a small vati or tadka pan, add the milk and saffron and heat over a low flame. Once the milk bubbles (it will only take a second), turn off the heat and let it sit for around 15 minutes until the saffron turns the milk golden.
Whisk all the ingredients. In a large mixing bowl, add the saffron milk, shrikhand, plain yoghurt, full-fat milk, fresh grated (or ground) nutmeg, and ground cardamom. Whisk until well incorporated — use a metal whisk, a wooden Indian ghotni, or a blender.
Chill the piyush. This is optional but highly recommended. Chill the piyush mixture in the fridge for a minimum of 15 minutes.
Garnish the piyush drink. Pour the piyush into small glasses then top with nuts and rose petals.
Notes
You can use either homemade shrikhand or store-bought shrikhand for this piyush recipe.