This Provencal dish -- made with pounded salt cod and pureed potatoes -- is a staple in French bistros. Riad Nasr of New York City's Balthazar restaurant shares his recipe and preparation technique.
In large bowl, completely cover cod in water, and soak for at least 24 hours, changing water every 2 to 3 hours.
Make two bouquets garnis: For each, bunch 2 bay leaves, 1 sprig rosemary, and 6 sprigs thyme together, and tie with kitchen string. In a medium saucepan, place cod with 1 head of garlic, 1 bouquet garni, the milk, and 1 cup water. Over low heat, bring to simmer. Cook until fish is flaky, about 10 minutes. Drain, and discard garlic and bouquet garni. When cool enough to touch, flake fish, and set aside.
Place potatoes in medium saucepan, and cover with salted water. Cook potatoes at a simmer until fork-tender, 15 to 20 minutes, and drain.
In small saucepan, add oil, remaining head of garlic, and remaining bouquet garni. Over low heat, warm the oil, about 10 minutes. Discard garlic and bouquet garni.
Put potatoes through a food mill while still warm. In the bowl of an electric mixer fitted with the paddle attachment, combine potatoes and cod on low speed until just incorporated. Slowly add the infused oil, then add 1 cup cream. Do not overmix, or potatoes will become pasty.
Garnish brandade with remaining 2 tablespoons warm cream and garlic confit. Serve with toasted croutons or bread.