Boil 1ltr milk when it comes to boil add the citric acid. Switch off the gas. Once the chenna settles sieve through muslin cloth, press out excess water, take it in a plate and press down. Do not knead. Put the remaining milk in a heavy pan and boil to half. Add chenna and boil till the mixture thickens. Stir continuously. Add sugar and continue to cook. Stir all the while till it softly thickens in a lump. Set in a tray, Then sprinkle the chopped nuts over it.