The night before you plan to cook, rinse the salt cod of its excess salt and put it in a large bowl with enough water to cover completely. Place in the fridge and let soak overnight, or as long as indicated on the package, changing the water 2 or 3 times.
Place the chickpeas in another large bowl with enough water to cover them by several centimeters/inches. Let them soak overnight as well.
Preparing the chickpea purée
Drain the chickpeas, then transfer them to a large pot together with the rosemary and garlic and a good pinch of salt. Add enough water to cover them by several cetemeters/inches. Simmer until very tender, adding water as needed to ensure they are always complete covered.
Transfer the chickpeas to a blender along with the garlic and a few rosemary leaves. Add a ladleful of the cooking water and blend at high. As you are blending, drizzle in the olive oil until you have a perfectly smooth and velvety purée. Add more cooking liquid if the purée is too thick for your taste. Keep warm until needed.
Marinating and Pan Searing the Salt Cod
Drain the salt cod well and pat dry. Cut into serving pieces. Pick off any bits of skin or bone you may find.
Place the cod fish fillets in a sealable container or plastic bag with the rosemary and garlic nestled among them. Drizzle with enough olive oil to coat well. Seal and let the cod marinate for about 2 hours, or until needed.
Remove the cod fillets and pick off any stray bits of rosemary or garlic, leaving a nice coating of oil.
Sear the cod fillets in a skillet over a lively heat, about 3-5 minutes per side depending on thickness, until cooked through and golden brown.
Finishing the Dish
Slather a 'bed' of the chickpea purée on each dish. Arrange your seared cod fillet over the purée and drizzle with a spoonful of the pan juices or a drizzle of your best quality olive oil. Sprinkle with minced parsley for color if desired.