Combine the salt, bay and thyme leaves, peppercorns and nutmeg in a spice grinder and grind until powdery.
Rub the duck legs with the garlic cloves and place both the duck and the garlic in a glass dish. Sprinkle the legs with the salt mixture, turning to coat. Cover and refrigerate for 2 days.
Preheat the oven to 200F.
Rinse the legs to remove the excess seasoning mixture and pat dry. Place the legs in a heavy flameproof casserole or Dutch oven, putting the biggest legs on the bottom, skin side down, and the smaller legs on top, skin side up. Add the garlic cloves and enough fat to just cover the legs and place the pan over medium heat. When you see the first bubble in the fat, remove the pan from the heat and place on a rimmed baking sheet in the oven. Cook, uncovered, until the meat is very tender and has shrunk away from the bone, 4 to 5 hours. The juices should run clear when a leg is pierced with a skewer. If any part of the legs is not quite covered, just turn the legs after 2 hours of cooking.
While the confit is cooking, place 3 wooden skewers in a saucepan and cover with water. Bring to a boil over high heat and boil for 5 minutes. Let cool, remove the skewers from the water, and set aside.6. Let the legs cool slightly in the fat. Break the wooden skewers into pieces and place them in the bottom of the sterilized jars or containers you are using to store the confit. (This is to prevent the confit from touching the bottom of the container.) Place the legs on top of the skewer pieces and ladle over the warm fat to cover the legs completely and fill the containers to the brim. Leave the confit on a wire rack to cool. The fat will contract as it cools, so once it is set, ladle a little more fat into the containers to seal them completely, then cover. The confit will keep, refrigerated, for up to 6 months. (When ladling the hot fat, be careful not to disturb any of the juices at the bottom of the pan. You do not want any of these juices to go into the storage containers. Strain the remaining fat through cheesecloth, leaving behind the juices. Pour the juices into a bowl and refrigerate the strained fat and juices separately. The fat can be reused several times until it becomes too salty. The confit juices will set into a jelly.)