In a medium pot, bring a few inches of water to a boil over medium heat, then salt the water. Trim the broccoli rabe and cut it into 1 1/2 to 2-inch lengths. Simmer in boiling water to reduce the bitterness, about 4 to 5 minutes, then cold shock in ice water and drain very well.
Heat a Dutch oven or large soup pot over medium-high heat with extra-virgin olive oil, a turn of the pan. Add the sausage and brown and crumble, 7 to 8 minutes. Add the onions, garlic and chile and cook a few minutes more. Add the thyme and lemon zest, then add broccoli rabe and season with a little nutmeg. Stir in the stock and the water and bring to a boil. Simmer a few minutes to combine the flavors. Turn off the heat, cool and store for a make-ahead meal. Reheat the stoup over low heat and bring to a low boil. Add the pasta and cook to al dente, about 10 minutes. Ladle the stoup in shallow bowls and garnish with cheese. Serve with crusty bread for mopping.
Recipe courtesy of Rachael Ray