The famous Portuguese baked salt cod with potatoes and olives

500g|1.25lb dried salt cod (soaked and hydrated)
6 medium potatoes, peeled, sliced thinly to rounds
2 onions, halved and cut to rings
1 teaspoon of garlic, finely chopped
18 pitted black olives
3 eggs hard boiled and sliced for garnish
1-1/2 tablespoons of chopped parsley for garnish
3/4 cup|180ml of olive oil, plus extra for frying.
equipment: ovenproof casserole

Put the salt cod in a pan, cover with water and heat to a boil, reduce the heat and simmer for 10 minutes or until the cod will just flake. Drain the cod, remove any skin and bones and then break the cod into medium sized chunks. Season with pepper.
Pre-heat the oven to 160⁰C|320⁰F.
Peel and slice the onions to rings, peel and chop the garlic finely.
Peel and slice the potatoes very finely and put in cold water to prevent browning.
Heat 3 tablespoons of olive oil in a frying pan, add the onion and fry over medium heat until the onions are translucent, add the garlic and fry for a few more minutes. Turn off the heat and mix in the the salt cod.
Oil the bottom and sides of oven proof casserole.
Drain the potato slices. Layer half the potato slices tightly over the bottom of the casserole dish avoiding any gaps, then layer on the salt cod mixture, finish by layering the remaining potatoes on top tightly. Pour the remaining olive oil over the top of the potatoes.
Bake the casserole in the pre-heated oven for 30-40 minutes or until the potatoes are cooked and lightly browned.
Whilst the casserole is cooking, hard boil the eggs, let them cool before peeling and slicing.
Garnish the casserole with the sliced eggs, olives and chopped parsley.