Place Chicken Stock (6 cup) in a large soup pot and bring to a very gentle simmer. If you have a rind from a wedge Parmesan or Pecorino or something of the like, drop it into the stock.
Cut the core end of the Escarole Lettuce (0.5 pound) off and place the leaves in a large bowl filled with cold water. Let sit for at least 5 minutes.
Scoop the leaves out and place in a colander. Roughly chop the leaves. You don’t want the leaves to be teensy, but you don’t want them to be so large that they are falling out of your spoon either.
Brown the Spicy Italian Sausage (1 pound) over medium heat in a skillet. (No need to add any oil to the pan to brown it — the fat from the sausage should be enough.) Once it is mostly cooked through, transfer it to a paper-towel lined plate to drain.
Add Cannellini White Kidney Beans (2 cup) to the soup pot.
Add a half pound of the escarole to the pot. Pat it down with a wooden spoon so that it’s submerged. Once it has wilted, add the sausage. Stir. If the soup looks like it needs more beans and greens, add them; if you like your soup on the brothier side, let it be.
Taste the broth. Add Kosher Salt (to taste) and Ground Black Pepper (to taste) to taste. Serve with Shaved Parmigiano-Reggiano (to taste)