Place the parsley, shallots and garlic (If using) into the food processor and give it a good blitz.
Use a spatula to push the sides down and then add the remaining ingredients.
Pulse blitz until you have a well combined butter.
Lay a large strip of cling film out on the bench , spoon the butter into a rough log onto the long edge of the cling film. (It will take up the centre 3rd of the the cling film. Carefully roll the cling film around the butter, then pinch the ends together and keep rolling it tight until you have a nice tight log.
Tie a quick knot in the ends of the cling film and store it in the fridge.