Begin by roasting the peanuts until aromatic and lightly browned. Once cooled, remove the skins by rubbing them between your palms, then crush the peanuts coarsely to retain some texture.
In a separate pan, combine the sugar or jaggery with ½ cup of water and heat over medium flame. Stir gently as it dissolves and begins to thicken. Continue boiling the syrup until it reaches a hard-crack consistency—test this by dropping a little into cold water; it should solidify and snap cleanly when broken.
Once the syrup reaches the correct stage, immediately add the crushed peanuts and mix thoroughly so every piece is well coated.
Grease a tray or flat surface with butter, then pour the hot mixture onto it. Quickly spread it out and roll it to an even thickness of about 1 cm while it’s still pliable.
Allow it to cool slightly, then cut it into neat squares. Once fully cooled, store the chikki in an airtight container to maintain its crispness.