Heat 3 % milk in a pot on medium heat and add butter to it (use a heavy pot if you have it). Sprinkle chopped almonds, rice and salt. Bring it to a boil. Stir frequently or the milk will burn. Cook till the rice is cooked and mixture is thickened. Then add evaporated milk and sugar.

Once the mixture has the consistency of pouring custard, add saffron, ground cardamom and nutmeg. Remove the pot from heat and pour in rose water, and chopped pistachios.

Chill before serving.

Put a sheet of saran wrap directly on the surface of the firni to prevent a skin from forming on top.