Preheat the oven to 375 degrees F (190 degrees C/gas 5), and find a snug-fitting pot for the chicken. Season it generously all over with salt and pepper, and fry it in the butter, turning the chicken to get an even color all over, until golden. Remove from the heat, put the chicken on a plate, and throw away the butter left in the pot. This will leave you with tasty sticky goodness at the bottom of the pan, which will give you a lovely caramel flavor later on.
Put your chicken back in the pot with the rest of the ingredients, and cook in the preheated oven for 1 1/2 hours. Baste with the cooking juice when you remember. The lemon zest will sort of split the milk, making a sauce, which is absolutely fantastic.
To serve, pull the meat off the bones and divide it on to your plates. Spoon over plenty of juice and the little curds. Serve with wilted spinach or greens and some mashed potato.