Drin the whey from paneer well and knead the paneer until the paneer is almost rolls into smooth soft dough.
In a flat frying pan add paneer, petha and cardamom mix it. Turn the heat to low and cook the paneer mixture stirring and pressing continuously until paneer starts coming together as soft dough. This should take about 4-5 minutes.
Turn off the heat and keep mixing the paneer like you are making dough. This is most important step to this dish; you are just cooking paneer enough to take out the rawness. If you over cook the paneer it will become crumbly.
Turn off the heat and transfer the mixture to the plate, let the mix sit for about 5 minutes, then divide into 12 equal parts or make the size of ladoo you prefer. Roll them between you palm and shape them in round balls. Garnish with pistachios.