1. peel and chop the potatoes (if you chop them finely then they will take less time to boil and produce a less lumpy mash).
2. Place the potatoes in a large pan of water with a little salt and leave to boil until very soft.
3. Meanwhile dice all the fish (appart from your smoked fish)into large chunks and place in a deep oven tray.
*Tip* its perhaps obvious but dont bother to dice your prawns/crayfish/shrimp (if using), just leave them whole.
4. place the smoked fish in a pan of milk and gently simmer,remove just as the milk starts to boil or it will get a skin.
*Tip* Putting the smoked fish in milk gets rid of its saltiness and flavours the milk.
5. put the milk aside to be used in the sauce and the potato later on.
6. Crumble the smoked fish over the other fish fillets in the dish, making sure to remove any bones and skin.
7. Pour some wine over the fish and add the zest and juice of the lemons.
8. To make the sauce melt the butter (60g) in a pan, when the butter has melted add the flour (40g) and stir together to make a paste.
9. Add 500ml of the reserved milk (remembering leave the remaining milk aside for the mashed potato)and whisk constantly so that the butter and flour mix in with the milk. If you do not whisk enough then the sauce will be lumpy.
*Tip* I use an electric whisk for this part but dont use an electric whisk if you're using a non-stick pan or your pan will get damaged. If all you have is a non stick pan you can transfer the sauce into a mixing bowl, whisk and then return to the pan.
10. The sauce should start to thicken as the milk boils, if it doesn't then add a little more flour, remembering to continue whisking.
11. Add some chopped parsley, a little salt and a load of black pepper (don't go overboard with the salt, remember that the salty fish has already flavoured the sauce).
12. When the potatoes are so soft that they are falling apart drain them, place in a large mixing bowl and mash. Add a teaspoon of butter, two tablespoons of cream cheese and the last of the reserved milk. Whisk the potatoes using an electric whisk (this will get rid of any lumps and make the potatoes extra light and creamy). Finlly stir in salt and pepper and the chopped chives.
13. Pour the sauce over the fish and carefully add the potato on top.
14. Add a sprinkling of parmessan (or other cheese)on top of the potato.
15. Bake in the oven on a high heat until the cheese turns golden brown.
16. Serve and enjoy!