Cod Melt in the Middle Fishcakes

cod 37.0% , white sauce 20.5% , wheat flour 18.0% , mashed potato 10.0% , rapeseed oil 6.0% , water 5.3% , potato flakes 2.6% , parsley 2.0% , single cream 1.0% , shallot 2.0% , lemon juice 0.0% , butterfat 0.0% , salt 0.0% , wheat starch 0.0% , dijon mustard 0.0% , white pepper 0.0% , yeast 0.0% , Raising agent 0.0%