Boil 500 gram cod, smoked haddock, or a combination, in: 200 ml whipped cream, 400 ml milk, onion rings, 2 cloves and bay leaf for about 10 minutes. Because of a miscommunication I ended up with 250 gram cod, it's clearly not enough.
Pour the milk through a sieve and cool the fish.
Flake the fish and layer the bottom of the oven dish with the fish, add two hard boiled eggs (sliced) on top of the fish. At this point boil floury potatoes, about 900 gram.
Make a roux from 50 gram butter and 50 gram flower. Add the milk-mixture.
Simmer the sauce for 10 minutes and add a few tablespoons fresh parsley, finely chopped. Add nutmeg, black pepper and salt.
Add the sauce to the oven dish and let it cool in the fridge.
While waiting, eat some oysters (optional).