Step 1Heat the oven to 325 degrees. Remove the bones and any excess fat from the lamb chops and cut the meat into large pieces. Season with salt on both sides.
Step 2Place the unpeeled garlic cloves in a saucepan and cover with water. Bring to a boil, simmer for 5 minutes, then drain. Cool, then carefully remove the peels.
Step 3Trim the fronds from the fennel bulbs and slice away the dried-out bottom of the bulb. Cut each bulb in lengthwise quarters, leaving the core intact to hold the fennel together.
Step 4Heat the olive oil in a large cast-iron or heavy-enameled pot over medium-high heat. Add the lamb and brown well on both sides. Be careful not to add so much lamb at one time that the pan is crowded. It's best to do this in two batches. Remove the browned lamb to a plate.
Step 5Reduce the heat to medium low, add the carrot and cook without stirring long enough for it to caramelize lightly on one side, about 2 to 5 minutes. Stir and cook 3 to 5 minutes more. Add the onion and cook until soft, about 3 minutes.
Step 6Add the white wine, bring the mixture to a boil and cook until it reduces to a syrup, about 7 to 10 minutes. Add the crushed tomatoes and cook until they thicken and darken, about 3 to 5 minutes.
Step 7Add 5 cups water and the beans. Slip the fennel quarters and the peeled garlic cloves into the pot, being careful not to break them up. Layer the lamb on top, pressing gently into the liquid. The tops of the lamb pieces will be sticking out of the liquid; this is OK.
Step 8Bring the mixture to a simmer and then press a sheet of aluminum foil close to the surface of the stew to form a loose cover. Cover the pot with a tight-fitting lid and place it in the oven. Bake undisturbed for 1 hour. After an hour, season the mixture with 1 1/2 teaspoons salt or to taste and a generous grinding of black pepper. Stir gently to avoid breaking up the fennel or crushing the garlic; return the pot to the oven.
Step 9Cook until the beans are soft and the lamb is tender, 2 to 2 1/2 hours. After 1 1/2 hours, check to see that the cassoulet is moist. If not, add up to 1 cup water, again stirring gently. Remove the pot from the oven and increase the heat to 400 degrees.
Step 10Cut away the crust from the baguette and cut the bread into cubes. Place the bread cubes and sage leaves in a blender; process to form crumbs. Start with 6 sage leaves and then smell to see if you want to add another two.
Step 11When the oven has reached 400 degrees, spoon the sage-flavored bread crumbs over the top of the lamb and beans in an even layer. Drizzle with a thin thread of olive oil and return the pot to the oven to brown the bread crumbs, about 20 minutes. Serve immediately.