Wash the potatoes and cut them into strips, chop mushrooms into thick halves.
Pour them into a tray and add the melted butter but do leave a small part of it for smearing the legs later.
Stir well and arrange the legs, salted and sprinkled with paprika.
Pour in 2 cups water, the beer, pieces of processed cheese, smear the legs or simply pour on the remaining butter.
Bake in the oven until it's left in just oil. Sprinkle with parsley before serving.