Boil a big pot of water with a little salt and cook the pasta till al dente. Drain and set aside.
Put a pan on medium heat and throw in the pork belly/bacon and onion and sauté for 5 minutes and then add the garlic and cook for a further minute.
Now tip in the spinach, mix and cover and cook for 5-7 minutes to allow the spinach to wilt and soften slightly (take care not to overcook the greens). Season with salt and pepper and pour in the stock and cream followed by the lemon juice (keep it on a gentle simmer)
Now add the pasta and mix well to ensure that the sauce coats all of it. Serve immediately.