Fill a tall-sided skillet with 1 inch of water, place over high heat and add the chicken sausages and a small splash of EVOO. Simmer the sausages until all the water evaporates then turn down the heat to medium-high and continue to cook, turning them every so often until the casings are brown and crisp.
Once you have the sausages going, heat a deep, large, heavy soup pot over moderate heat. Add 1 turn of the pan of EVOO, about 1 tablespoon, and add the pancetta. Cook, stirring frequently, for 2-3 minutes or until the pancetta is crisp.
Remove all but 1 tablespoon of fat from the soup pot then add the garlic, red pepper flakes, onions, bay leaf, a little salt and pepper, and cook until the onions are tender, about 4-5 minutes. Add the escarole and wilt them down to fit them into the pot. Add the nutmeg and the chicken stock and beans, turn the heat up to high and bring up to a bubble. Lower heat and simmer for 5 minutes. Taste and re-season with salt and pepper.
While the stoup is cooking, place the parsley leaves and lemon zest on your cutting surface, run your knife through the parsley until it's well-chopped and the lemon zest is mingled with the parsley. Reserve.
Remove the browned chicken sausages from the skillet and slice. Divide the stoup and the sliced chicken sausages between 4 serving bowls. Sprinkle each bowl with some to the parsley/lemon zest mixture and some shaved Parmigiano Reggiano.