Bring the cow’s milk to a boil in a deep pan. Lower heat, add whey and stir continuously till the milk curdles completely. Strain through a piece of muslin and immediately place the muslin potli on ice to stop the cooking process.
Squeeze to remove the excess moisture. Transfer chenna to a plate and knead with the heel of your hand till smooth. Add powdered sugar, rose water and desiccated coconut and mix well to make a medium soft dough.
Divide the mixture into sixteen equal portions and shape into laddoos. Roll laddoos in crushed pistachios and arrange on a serving plate. Chill.