Ingredients

Instructions

1Heat the oven to 180°C/350°F/gas mark 5. Lightly butter a medium roaster

2 Place the fillets of fish in a medium saucepan. Add 650ml milk, bay leaf, a couple of stalks of parsley and the peppercorns

3 Place the pan on a low heat and let the milk heat up gently, as soon as it comes to a simmer, switch off the heat and cover the pan. The fish will continue cooking in the hot milk

4 Meanwhile, peel the potatoes, cut them into even pieces using a sharp knife, put them in a pan, we used an 18cm saucepan, add just enough water to cover, bring to the boil and then simmer for about 10 minutes or until the potatoes are tender

5Drain, add a little knob of butter and a little milk and some freshly ground black pepper

6 Then, take the fish out of the milk and carefully flake the fish into big chunks and put into a buttered medium roaster. Add the prawns. Stand a sieve over a large jug and tip in the fish milk mixture

7 Make the white sauce. Put 50g of butter in a small milk pan and melt over a gentle heat. Don't let it brown as this will affect the colour and flavour of the sauce

8Add 50g flour and cook for one minute stirring constantly to make a smooth glossy paste

9 Then, using the remainder of the milk, add a little milk, stir until the milk is completely mixed in. The mixture will go very thick, but mix until it is smooth, then add a little more milk and stir again and continue like this until you have used up all the milk, making sure that you mix really well between additions as this is what will stop your sauce from being lumpy

10 Continue to cook over a low heat and let the sauce cook very gently for 5-6 minutes, stirring every now and then

11Use 60g of butter and 60g flour in the white sauce and then add the fish milk. Add the chopped fresh parsley

12 Finally, pour the sauce over the fish and very gently mix together

13Spoon the mashed potato over the top. Sprinkle over the cheese. Bake for 30-35 minutes until golden and bubbling.