Mix the chopped parsley into half the butter and then divide into four pats.
Put one pat into each cleaned fish, then place them in an oven-proof dish and rub salt and white pepper into them.
Pour the wine around, cover and cook in a moderate to hot oven (350Â° F.-400Â° F. electric; gas regulo 4-5) for 20 minutes.
Add the rest of the butter cut into small pieces and the juice of the lemon.
Cover again and cook for another 10 minutes.
It can be served hot or cold; if the latter, chill and it will be a soft jelly.
If served hot, cauliflower sprigs are excellent with this dish.
In eighteenth- and nineteenth-century Ireland, the florets were cooked in a little milk to barely cover, with a knob of butter and salt and pepper.
The liquid almost evaporates and gives the cauliflower a very good flavour.