Method
Prep:40min  ›  Cook:30min  ›  Ready in:1hr10min 

1. Pour the 750 ml (1¼ pints) milk into a wide frying pan. Add the haddock and bay leaf. Bring to a gentle simmer, then cover and cook for about 5 minutes or until the haddock is just cooked.
2. Lift out the fish with a draining spoon and leave to cool slightly, then peel off the skin and break the flesh into large flakes. Set aside. Strain the milk and reserve 600 ml (1 pint), as well as the bay leaf.
3. Put the leek in the frying pan and add the reserved milk and bay leaf. Cover and simmer for 10 minutes or until the leek is tender.
4. Meanwhile, cook the potatoes in a saucepan of boiling water for about 8 minutes or until they are just tender but not breaking up. Drain. Preheat the oven to 190°C (375°F, gas mark 5).
5. Remove the bay leaf from the leeks and discard. Mix the cornflour with the remaining 3 tbsp cold milk to make a smooth paste. Add to the leek mixture and cook gently, stirring, until slightly thickened.
6. Take the pan from the heat and stir in the watercress, which will wilt. Season with salt and pepper to taste. Add the flaked haddock, folding it in gently. Transfer the mixture to a 2 litre (3½ pint) pie dish.
7. Arrange the potato slices on top of the fish mixture, overlapping them slightly. Sprinkle with the cheese, and season to taste. Bake for 25–30 minutes or until the fish filling is bubbling and the potatoes are turning golden.
8. Sprinkle the top of the pie with parsley and allow to stand for about 5 minutes before serving.

Each serving provides

Excellent source of iodine, vitamin B12. Good source of calcium, niacin, potassium, selenium, vitamin B1, vitamin B2.

Some more ideas

Use 2 sliced leeks. Omit the watercress and instead, in step 4, add 125 g (4½ oz) baby spinach leaves to the potato slices for the last 1–2 minutes of their cooking time. Drain well. Make a layer of the potatoes and spinach on the bottom of the pie dish. Spoon the hot fish and leek sauce over the top, sprinkle with the cheese and grill under a moderate heat for 5–10 minutes or until bubbling and golden.

Plus points

Potatoes do not contain as much vitamin C as many other vegetables, but they are a valuable source of this vitamin because they are eaten so frequently and in such large amounts. * Smoked haddock is an excellent source of iodine and provides useful amounts of vitamin B6 and potassium. Undyed smoked haddock is now widely available as an alternative to the vibrant yellow-dyed version, which may cause a reaction in susceptible people. Beware of the sodium content and reduce added salt. * Watercress, like other dark green leafy vegetables, is an excellent source of many of the antioxidant nutrients, including beta-carotene, vitamin C and vitamin E.