Cook the fish in a little water with ginger, chopped green chillies, a few drops of vinegar and required salt. Cool and flake the fish into big pieces.
Take a bowl and put the fish flakes. Add butter and biscuit crumbs. Mix gently and put the fish mixture into a pie dish. Press down firmly.
Bake the above mixture at 375 degree for 6 minutes.
Whisk the egg lightly and add minced onion, cheese, pepper and milk. Mix together and spread over the baked fish mixture. Sprinkle some biscuit crumbs on top. Bake till firm.