Put the soaked Great Northern beans into a large pot with the salt pork or bacon, the halved onions, smashed garlic, bouquet garni, and chicken stock. Bring everything to a gentle simmer, then cook uncovered for about 1 hour. Stir now and then, and keep going until the beans are nearly tender.

While the beans cook, heat the oven to 350°F. Then remove the bacon from the pot and cut it into 1-inch pieces. Strain the beans and save the cooking liquid, since you will need it later. Discard the onions and bouquet garni.

Prick the sausages and place them in a 10-inch skillet with about 1/4 inch of water. Cook them for about 5 minutes, or until the water has evaporated. Then brown them on all sides and slice them into 1-inch pieces.

After that, add 2 tablespoons duck fat or olive oil and the chopped onion to the skillet. Cook for about 5 minutes, then add the minced garlic for 1 minute.

Next, add the white wine for 1 minute, followed by the tomatoes for about 5 minutes. Season well with salt and pepper.

In an 8-quart casserole, spread one-third of the beans across the bottom. Add half the bacon, sausage, and duck, then spoon over half the tomato mixture. Repeat with another third of the beans and the remaining bacon, sausage, duck, and tomato mixture. Finish with the last of the beans.

Season the reserved bean liquid, then pour in enough to just reach the top of the beans.

If you want, assemble the cassoulet ahead of time and refrigerate it for several hours before baking.

When ready, sprinkle the bread crumbs over the top and dot with the remaining 2 tablespoons duck fat. Bake for 45 to 75 minutes, until a deep golden crust forms.

While it bakes, break the crust with the back of a spoon 3 or 4 times so a new crust can form underneath. Then let it rest for 10 to 15 minutes before serving in shallow bowls with a green salad.