Set milk to a boil in a heavy pot and keep on stirring it.Once the milk is boiling, switch off the flame and immediately add vinegar to it. Stir gently 2-3 times. You will see that the milk starts curdling. Let the curds form, don't stir a lot.
Once you see that all the milk has curdled and a greenish whey has separated, strain the curdled milk through a muslin/cheese cloth. Pour some cold water to remove the traces of vinegar and to cool it down. Tie the cheesecloth and hang it for about 20-25 minutes to remove some liquid from the chenna.
Transfer the chenna to a wide dish and using the base of your palm, knead the chenna for around 5 minutes to a smooth grain free dough. Pinch small grape size portions and make smooth round balls. Set aside, covered.
In a wide pot, transfer the sugar and water for the syrup, add the cardamom pods and bring it to a rolling boil. Add the rose syrup, let boil again and slowly add the chenna balls.
Dont lower the heat, let cook for 10-12 mins. Meanwhile transfer a little (about ½ cup) sugar syrup to a bowl of ice. Immediately add cooked chenna balls to ice bath and let cool off for 5-8 mins.
Mix rose water with the remaining syrup in the pot and cool down the syrup. Transfer the cooled chenna balls and syrup to a container together and let soak for 6-8 hours. Discard the syrup in ice bath.