In a wide, deepish pan, add the milk and cold water to give about an inch depth of poaching liquid. Add the Bayleaves then poach the smoked fish (cut into bite sized pieces) until opaque and cooked through.

Drain the cooked fish pieces in a sieve over a bowl and return any liquid to the poaching pan.

Repeat for the other two fish and arrange in your ovenproof dishes making sure there are even parts of each of the three varieties and they are equally distributed in the dish.

Add the large prawns (No need to poach if already pink and cooked) then sprinkle the mixed herbs on top and season well with a little salt and plenty of black pepper

Next, strain the remaining poaching liquid to remove any scum, lumps or bayleaves and add the stock pot made up with a little boiling water along with the mustard and whisk. When simmering, slowly add the instant potato whilst still whisking until all added. The resulting sauce needs to be like a thin wallpaper paste that still pours but not too sloppy or wet. If too thick, just add some more water and if too thin, mix a little cornflour with cold water and whisk in whilst simmering to thicken up. Season the sauce to taste and then pour over the fish mixture in the oven dishes

Finally, peel and cut the potatoes into chunks, rinse and boil in a pan with some salted water. When cooked through, drain and mash, adding the fromage frais. You could also add some wholegrain mustard to the mash to give it more depth of flavour if you wish. Spread the mash on top of the fish mixture and roughen with a fork then bake in a moderate oven for 30-40 minutes until piping hot and starting to brown on the top