Milk-Braised Salt Cod with Potato Gratin

Method

1. Fill a pot with water, add bay leaves, a clove of garlic (smashed with skin on), and a strip of lemon zest. Bring to a boil, then add the desalted salt cod and cook for 10 minutes.
2. While the cod cooks, peel the potatoes and place them in a bowl of cold water. Cut them into rounds about 5 mm thick. Return the slices to cold water without stirring to preserve the starch.
3. Slice the onions and put them in a bowl of cold water. Stir them briefly to reduce their strong flavor.
4. After 10 minutes, drain the cod and let it cool slightly. Remove the bay leaves, garlic, and lemon zest from the cooking water.
5. In the same cooking water, add the potato slices and cook for 5 minutes from the moment the water boils again.
6. Once the cod is cool, remove any bones and shred it into small pieces.
7. Drain the onions well and set aside.
8. Drain the potatoes (they should still be firm). While hot, season with nutmeg, black pepper, and a drizzle of olive oil. Add about 100 ml of cold milk to stop the cooking. Mix gently, taste, and adjust salt if needed. Set aside.
9. In a pan, heat some olive oil and sauté the onions until golden. Add the shredded cod and mix well. Pour in the remaining 200 ml of milk and cook for 7–8 minutes until the milk is reduced by half and forms a creamy sauce.
10. Preheat the oven to 190°C (375°F). Lightly oil the bottom of a baking dish. Make a first layer of potatoes, then a layer of the cod mixture, then a final layer of potatoes. Pour any remaining liquid from the potato bowl (the 100 ml of milk) over the top.
11. Add the fresh cream (100 ml) over the layers. Sprinkle with nutmeg, black pepper, and a generous amount of grated Parmesan cheese.
12. Bake at 190°C for 25–45 minutes, checking occasionally. If the dish looks dry, it may need less time; if too liquid, more time. Adjust accordingly.
13. Let it rest for a few minutes before serving.