Place beans in a large pot and cover with cold water.  Soak the beans for 8 hours or overnight.  

Drain the beans, then cover them with 2-inches of cold water and bring them to a boil over medium-high heat, cook for 10 minutes.  Drain and reserve.

In a 6-qt. Dutch oven or large braiser set over medium-low heat, add half of the duck fat. When the fat melts, add the cubes of salt pork. Stir occasionally to brown on all sides. Transfer to a plate and reserve.

Prick the sausages in several places to keep them from splitting. Add the sausages to the pot turning until well brown on all sides.  Remove to the plate and reserve.

Add half of the pork tenderloin cubes to the pan and sear them until brown. Place them on a plate and continue browning the remaining pork cubes.  

Melt the remaining fat/oil in the pan, then add the carrots, fennel, chopped onion, and garlic.  Sauté for 1-2 minutes.

Add the drained beans, Herbs de Provence, bay leaves, salt, and pepper.

Pour the chicken and duck broth into the pot, and stir to combine. Nestle the clove-studded onion into the mixture,

Bring the pot to a boil over high heat, then reduce the heat to medium-low, cover and simmer for 45 minutes or until the beans are tender to the al dente stage.

Preheat the oven to 300°F.

Stir in the browned sausages and pork cubes.  Cover the pot and transfer to the oven. Cook for 2 hours. 

Remove the pot from the oven, and discard the clove-studded onion. Lay the duck legs on top of the cassoulet, snuggling them lightly into the juices but leaving them partially exposed.  Cover the pot and return to the oven for 20 minutes for the duck legs to heat through.  

Transfer from the oven, remove the cover, and brush the exposed duck legs lightly with olive oil. Turn the oven to broil and cook until the duck legs are golden brown and the skin is crisp, about 5-6 minutes.  

Transfer from the oven, garnish with chopped rosemary and thyme leaves.  Serve immediately directly from the pot with crusty bread.