1. Boil a full kettle and once boiled, pour the water over the pork belly, skin side up. The pork needs to be held up at an angle so the water runs off the pork immediately. This helps to achieve great crackling.
2. Pat dry and rub both sides with three tablespoons of olive oil, fennel seeds and half the chopped rosemary. Sprinkle liberally with salt and pepper.
3. Cut the ends of each of the onions and cut in half, lay them on the bottom of a roasting tray to create a trivet for the meat. This will stop the bottom of the meat burning and will also give the sauce a lovely flavour.
4. Preheat the oven to 220°C and roast the pork for 20 minutes. Remove from the oven and add 240ml of the chicken stock, return back to the oven for a further 20 minutes before adding another 240ml chicken stock. At this point the skin should have blistered evenly to give a great crackling. If the crackling isn't ready, return to the oven for a further 20 minutes. Turn the oven down to 135°C, add 10ml of chicken stock and roast for a 2 1/2 hours, check the pork every 20 minutes and top up with water if the stock dries out.
5. Once cooked, remove the pork from the tray and allow to rest for 15 minutes.
6. While the pan juices are still warm, scrape the pan to release all the flavor and strain the juices into a small saucepan. Bring to the heat and reduce a little, being careful not to add any seasoning as the pan juices have reduced a lot during cooking. Set aside until serving.
7. Meanwhile to make the beans, bring a saute pan to the heat, add the remaining olive oil and butter, when bubbling add the shallots and saute on a medium heat for three minutes or until softened. When the shallots are soft, add the garlic and cook for a further two minutes before adding chopped rosemary, stir briefly and add the cream and remaining 150ml of chicken stock. Bring to the boil and reduce the heat and allow the sauce to reduce by a third. Add the beans and stir to warm through. Season and stir through the flat leaf parsley and keep warm until needed.
8. Cut the pork into six even pieces, keeping the crackling intact. The easiest way to do this is with a serrated knife, skin side down. Serve the beans first, top with a piece of pork and drizzle with the pan juices.