Rub the spices all over the pork and chill in the fridge for 12 hours (or at least 2 hours). The longer the meat has to marinate, the tastier it will be.
In a pan melt the butter and brown the pork on all sides.
In a deep saucepan (or casserole dish) bring the milk to the boil and place the pork inside. Simmer for 1 hour, gradually add butter as the milk evaporates. Stir often, because the mixture will thicken and the pork may stick to the bottom.
Slice the pork, place on a platter and pour sauce over. Serve with potatoes and green salad.