1. Pat chicken dry with paper towels and season with salt and pepper. Heat oil in Dutch oven over medium-high heat until just smoking. Add chicken, skin side down, and cook until well browned, 6 to 8 minutes. Transfer chicken to plate. Discard skin.

2. Drain off all but 1 teaspoon fat from pot and reserve 1 tablespoon fat for dumplings. Return pot to medium heat. Add fennel bulb, onion, carrots, and 1/2 teaspoon salt and cook, stirring occasionally, until vegetables soften and begin to brown, about 5 minutes. Add wine and cook, scraping up any browned bits, until almost dry, about 2 minutes. Return chicken to pot; add broth and Parmesan rind and bring to boil. Reduce heat to low, cover, and simmer until chicken is tender and registers 175°F, about 30 minutes. Transfer chicken to plate. Discard Parmesan rind. Cover broth and remove from heat. When cool enough to handle, use 2 forks to shred chicken into bite-size pieces. Discard bones.

3. While broth is simmering, adjust oven rack to middle position and heat oven to 350°F. Pulse bread in food processor until finely-ground, 10 to 15 pulses. Measure out 1 cup bread crumbs and transfer to parchment paper-lined rimmed baking sheet (set aside remainder for another use). Toast until light brown, about 5 minutes. Transfer to medium bowl, reserving sheet and parchment, and let bread crumbs cool completely.

4. Pulse shredded Parmesan in now-empty food processor until finely-ground, 10 to 15 pulses. Transfer Parmesan to bowl with cooled bread crumbs and add reserved 1 tablespoon fat, egg whites, lemon zest, 1/8 teaspoon pepper, and nutmeg. Mix until thoroughly combined. Refrigerate dough for 15 minutes.

5. Working with 1 teaspoon dough at a time, roll into smooth balls and place on parchment-lined sheet (you should have about 28 dumplings).

6. Return broth to simmer over medium-high heat. Add escarole and chicken and return to simmer. Add dumplings and cook, adjusting heat to maintain gentle simmer, until dumplings float to surface and are cooked through, 3 to 5 minutes. Stir in fennel fronds. Season with salt and pepper to taste, and serve.

TO MAKE AHEAD: Prepare recipe through step 5. Refrigerate broth, shredded chicken, and dumplings separately for up to 24 hours. To serve, proceed with step 6 as directed.

Serves 4 to 6