Place the haddock and the salmon in a large, wide frying pan with the bay leaf, parsley stalks, onion and stock. Bring to the boil, then reduce the heat and cook very gently for 5-6 minutes until the fish is just cooked. Remove the fish with a slotted spoon and transfer to a plate, add the wine to the pan and reduce by fast boiling until about 300ml remains and reserve.

Melt the butter in a medium saucepan and gradually stir in the flour. Cook gently for 2 minutes, then gradually stir in the still warm stock and wine, followed by the milk. Cook gently, stirring frequently, for about 10 minutes until thick and smooth. Gradually stir in the cream, then season to taste with nutmeg, salt and pepper.

Wilt the spinach in its own juices in a large covered saucepan. Drain well, pressing out excess moisture.

Flake the cooked fish into bite-sized chunks and arrange in a wide ovenproof dish with the spinach, prawns and quartered eggs.

Stir the chopped parsley and half the dill into the sauce and carefully pour over the fish, covering it evenly.

Cook the potatoes in boiling salted water for 15-20 minutes until tender, then mash. Fry the leeks gently in half the butter until soft but not browned and beat into the potatoes with sufficient milk to make a smooth mash. Beat in the remaining dill and season to taste.

Preheat the oven to 190C, 375F, Gas 5. Spoon the potato over the fish, smooth down, then make ridges using a fork or knife. Dot with the remaining butter. Cook for 40-45 minutes until the filling is bubbling and the topping is golden brown. Serve immediately.

Cook's tip

If you like smoked fish, substitute some undyed smoked haddock, all skin and bone removed after cooking, for some or all of the salmon. For a more everyday fish pie omit the wine (use more stock) and prawns and substitute milk for cream. Season the sauce with a little lemon juice to make up the acidity lost with the wine.