Have your fishmonger clean, head and tail the fish. Combine finely chopped parsley with 2 to 3 tablespoons softened butter and as many pinches of powdered thyme. Lay the fish in a well-buttered baking dish and dust lightly with flour. Season to taste with salt and freshly ground black pepper; dot with butter; cover with a well-buttered piece of paper or foil and bake in a hot oven (450°-M7) until fish flakes easily with a fork. The roes should be lightly flavoured and cooked in the dish with the fish. Serve immediately.