Fish pie with prawns and cheesy leek mash topping

Method

1. Put 450ml of the milk and the cream into a large pan and bring to the boil. Add the white and smoked fish fillets and simmer for 5-6 minutes, until just cooked through. Lift the fillets onto a plate to cool slightly and strain the liquid into a jug.
2. When the fish is cool enough to handle, break it into large flakes, discarding the skin and any bones. Spread over the base of a 1.75-litre shallow ovenproof dish and scatter over the prawns and chopped eggs.
3. Melt 50g of the butter in a pan, add the flour and cook, stirring, for 1 minute. Pull the pan off the heat and gradually stir in the reserved cooking liquid. Return to the heat and slowly bring back to the boil, stirring all the time. Simmer the sauce for 5 minutes, stirring occasionally. Season to taste, stir in the parsley and pour over the fish. Leave to go cold.
4. Cut the potatoes into large chunks and boil in salted water for 20 minutes or until soft. Meanwhile, melt the remaining 50g butter in a small pan, add the sliced leek and cook gently for 3-4 minutes, until tender.
5. Drain the potatoes well, return to the pan and mash until smooth. Stir in the buttery leek, cheese and a little of the remaining milk to make a spreadable but not too wet mash. Season with salt and freshly ground black pepper.
6. Preheat the grill to medium. Spoon the mash over the top of the pie and spread it out in an even layer. Rough up the surface with a fork or the back of a spoon and grill the top of the pie for 15-20 minutes, until bubbling and golden brown.