Add the 3 cups sugar to a pan and start heating in low flame. Add the dried pethas into the pan and mix them thoroughly in the same low flame. After 10 minutes or so, the sugar starts to melt as shown.
Keep heating in low flame and here is when you can add the cardamom powder or rose essence if needed. This is optional, but adds a wonderful taste to the Agra-ka-Petha!
Wait until the sugar syrup dries up, switch off the flame now.