Take a heavy bottom pan and add milk to it.
Bring the milk to a boil.
Lower the heat to medium and let a layer of malai form on top.
Using a skewer, push the layer of malai on the side of the pan.
Keep repeating the process and keep pushing the malai on the sides.
Cook the milk for 1 to 1.5 hours, till it is reduced to quarter.
Add the laccha collected on the sides back to the rabri.
Add sugar and rose water and cook for another minute.
Pour the rabri in earthen pots for more flavor or else just transfer in a serving bowl.
Garnish with almond and pistachio slivers.
Either serve hot or chill in refrigerator for a few hours before serving.