Put the pancetta in a small frying pan over a medium heat and leave until the fat starts to melt then turn the heat up and fry until the cubes start to brown. Add the sprouts and chestnuts and stir. Add a knob of butter, followed by the cabbage and season well. Cook until the edges of the sprouts and cabbage start to colour. Add another knob of butter followed by the potato and stir it through the mix then pat it down. Cook until the potatoes start to brown on the bottom then turn over in batches – you want there to be plenty of browned, crisp bits throughout the squeak, so continue doing this for a while. If you’re serving this on its own (a fried or poached egg on top makes a good supper dish) make up a sauce with the yoghurt and chilli sauce to go with it, otherwise serve as a side dish with the parsley on top.