How to cook
Wash the potatoes and arrange them in a deep tray, salt them and add the remaining butter.
Put the meat on top and pour 1 1/2 cups water, cover with foil and bake in a preheated 320°F (160 °C) oven for 1 hour.
Remove the foil and baste the meat with the released sauce, finish baking until the meat is ready, basting it at least one more time.
For a crispy crust, turn the oven's heat up shortly before it's ready.