MAKES ENOUGH FOR 2 DINNERS, EACH SERVING 4
1 1/2 pounds (680g) skinless, boneless salt cod
1 1/2 cups (355ml) milk
2 thyme sprigs
1 bay leaf
10 black peppercorns
3 allspice berries
1 1/2 pounds (680g) white potatoes, peeled and cut in 1-inch (2.5cm) cubes
8 cloves garlic, peeled
Leftover roasted garlic cloves, from the Roasted Garlic Dressing
3 tablespoons extra-virgin olive oil
1 teaspoon finely grated lemon zest
Pinch of cayenne
Large pinch of grated nutmeg
1/2 cup plus 2 tablespoons (150ml) crème fraîche or heavy cream
Kosher salt and freshly ground black pepper
4 tablespoons (60g) cold unsalted butter
3/4 cup (45g) panko
1 Rinse the salt cod well and rub off any salt. Soak in 2 quarts (1.9L) cold water for at least 8 hours. Drain and change the water every few hours (an overnight soak without changing is fine).
2 In a saucepan, heat the milk plus 1 ½ cups (355ml) water over medium-high heat. Add the cod, thyme, bay leaf, peppercorns, allspice berries, and clove. Adjust the heat to maintain a bare simmer. Cook until the fish flakes easily, about 15 minutes. Remove the fish and hold at room temperature.
3 Meanwhile, in a separate pot, cover the potatoes with water and bring to a boil. Add the garlic and a good pinch of salt. Boil the potatoes until they’re soft, about 15 minutes, then drain the potatoes, reserving the cooking liquid.
4 Put the potatoes and roasted garlic in a large bowl. With your fingers, flake the cod on top. With a potato masher, roughly blend the potatoes and cod. Add the olive oil, lemon zest, cayenne, and nutmeg to taste. Switch to a wooden spoon and stir in ½ cup (120ml) of the crème fraîche and beat well to combine. Beat in about ½ cup (120ml) of the potato cooking liquid (strained) to lighten the mixture so it has the texture of soft mashed potatoes. Taste and adjust the seasoning; it will probably need salt and pepper.
5 Use 1 tablespoon of the butter to grease a low-sided 3-quart (2.8L) baking dish. Transfer the brandade mixture to the buttered dish and smooth with a spatula. Paint the top with the remaining 2 tablespoons crème fraîche and sprinkle with the panko. Dot the top with the remaining 3 tablespoons butter. Cover and store in the fridge.
6 The day of: Bring the brandade to room temperature, then heat the oven to 400 ° F (200 ° C). Bake until golden and bubbling, about 20 minutes.