Fish Pie - quick 'n easy

forgot to take a photo - so this is not my fish pie pic - but mine looks very much like this one :)
 There probably look like a lot of instructions here, but this dish is pretty easy to make.  
You can completely cheat and use all ready-made/bought in ingredients to make it even quicker.

This dish can be made in advance and kept in the fridge.  

Preferably use the same day as the sauce may separate.

Ingredients:
Fresh Salmon - enough for 4
2 pkts. of smoked trout (approx. 4-6 ozs.)
1 pack of prawns - frozen or fresh - amount to your own taste
8ozs. chestnut mushrooms

1pt. milk (full cream milk is nice but not essential)
large knob of butter, and small amount of oil for frying mushrooms
salt and black pepper
few bayleaves - dried or fresh
dried or fresh herbs - oregano, small amount of basil and thyme
Approx. 3 packs (enough for your amount of people) of bought-in mashed potato - (or home -made)
2 tablespoons plain flour
1-2ozs. butter

1. Saute the sliced mushrooms in some oil and a little butter, add a small pinch of thyme - set aside. Reserve the liquid to add to the white sauce*.

2. Place the salmon in a buttered oven-proof dish, pour over the milk, add some knobs of butter, seasoning, and the bayleaves, cover and bake for approx.20 mins.

Baste - if the milk doesn't completely cover the fish.

Oven: 180/190 C.  (The fish can of course be cooked in the micro)

Remove fish from the oven, reserve the milk for the sauce, let it cool, remove the skin from the fish and discard, and put the pieces of fish into another buttered oven-proof serving dish.

3. Cut the prawns into pieces and scatter on top of the salmon - same with the smoked trout and  mushrooms.  Add some dried herbs and season - (salt to taste).

4. Make the *sauce: (in the micro) - stirring frequently -

In a large Pyrex jug (or other) pour 1pt. of milk - (using the milk from poaching the salmon and the mushroom liquid, if there is any) -  adding more milk to make up to a pint, if necessary.

approx. 2 ozs. of butter.

.... mix a small amount of this milk with

2 tablespoons of plain flour, salt and pepper (not too much salt as the trout may be salty) then add the creamy smooth mix to the larger amount of milk.  Stirring it in well.

Zap in the micro. Stir frequently until

The sauce is a nice, 'thickish' consistency - let it cool then pour over the cooled fish mix.

5. Place the mashed potato on top**, dot with some knobs of butter and

bake until the potato starts to colour on the tips, and you can see the sauce is bubbling. (approx. 180/90 C for at least 1/2 hr.)

Turn the heat down slightly while keeping warm.

**You can add grated cheese to the top of the potato, but I dont usually do this.
You can also add some lovely chopped corriander in with the fish.  I prefer this to parsley.