If the cod is salted, soak it at least for dozen hours in cold water, changing the water 3 or 4 times. Drain the cod and place it in a saucepan with enough water to cover the fish by 3 cm. Bring to boil over high heat. Reduce the heat and simmer for about 20 minutes. Drain thoroughly. Remove and discard any skin and bones; shred the fish. Set aside. Deep-fry the potatoes, turning them about in the hot oil for 3 to 5 minutes or until they are crisp golden. Transfer the potatoes to a 9 x 33 cm Pyrex baking dish and set aside. In a heavy skillet, heat the olive oil over moderate heat. Add the chopped onions and saute until transparent. Add the shredded cod, the half and half and simmer over very low heat, stirring frequently, for about 10 minutes. Put this mixture over the potatoes in the baking dish and pour the beaten egg over it. Add a little more olive oil, according to taste and bake in a 350 degrees oven for about 20 to 30 minutes or until golden. Serves 4 to 6 people.