Well ahead of time and ideally the day before: if using fresh cod, salt as described.
Rinse the salted fish under cold running water for 30 minutes. Cut the fish into pieces.
Peel the potatoes and cut them into chunks. Separate 2 of the eggs. Remove the stalks from the parsley and chop the leaves.
Put the fish in a saucepan with the milk, parsley stalks and bay leaf. Bring to the boil, turn down the heat and simmer for 4 minutes, or until just done. Strain through a sieve, reserving the milk. When the fish is cool enough to handle, remove and discard the skin, bones and bay leaf.
While the fish is cooking and cooling, cook the potatoes in a large pan of rapidly boiling lightly salted water until just tender. Drain and return to the pan.
Ideally using an electric whisk, beat the potatoes with the cod. You can also use a masher or a fork, but do not use a food processor which will turn the mixture into glue.
While whisking or mashing, add 1 whole egg and the whites of the 2 separated eggs. Then dribble in 1—2 tablespoons of the reserved milk and 1 tablespoon of olive oil, until you have a smooth thick purée. You want to achieve a consistency which you can handle and shape, so do not allow the mixture to get too slack. If liked, also grate and add the Parmesan at this stage. Season with grated nutmeg and pepper. If using salted fillets, you are unlikely to need to add salt, but you make that decision when you taste.
Mound into a bowl and refrigerate for at least 2 hours, before attempting to make the croquettes.
When ready to prepare the croquettes: if using the crisps, put them in a tray and crush with a rolling pin. Put the flour seasoned with 1 teaspoon of salt and ½ teaspoon of pepper in a large soup bowl and whisk the egg yolks with the remaining whole eggs and put into a similar dish.
Using a tablespoon, scoop out enough mixture to make a croquette about 5 cm/2 in long with a diameter of 3 cm/1¼ in. Drop it into the flour and, using one hand, roll the croquette in it to coat. Then coat it with egg and finally, using your other hand, roll it in the crushed crisps or crumbs. Transfer to a baking tray. Repeat until you have used up all the mixture. If you run out of the egg mixture just whisk up another whole egg at a time.
After they are done, drain briefly on paper towels before serving. If cooking in batches, keep each batch warm on a pile of paper towels in a low oven with the door open until all are cooked.
If serving them on their own, cut a wedge of lemon for each plate.
© 1995 Alastair Little. All rights reserved.