Well my mum told me this one.
I tend to use white fish and boil it from frozen in milk, some big prawns and salmon goes nicely too not in the milk thoughlol. A tin of condensed mushroom soup, couple of bay leaves, some frozen petit pois makes it look better with some green. Put it all togther and cover with cheesy mash. Voila! Tastes yummy!
In the oven for about 1hour if fish is uncooked medium to high heat.