Rigatoni with Sausage, Spinach, and Goat Cheese

1.Bring a large pot of salted water to a boil. Heat olive oil in a large saute pan over medium-low heat. Add the onions and a pinch of salt and cook until translucent, about 4 minutes. Add the sausage and use a fork to crumble the sausage into the pan. Increase the heat to medium-high, and fully cook the sausage, adding some of the pasta water to deglaze the pan.
2.Cook the rigatoni until just shy of al dente. Before draining, reserve about 1 cup of the cooking water.
3.Add the pasta to the pan with the sausage, reserving the cooking liquid, and add the parsley. Add the spinach and tomatoes and cook, tossing, until the spinach has wilted. Add some of the reserved cooking liquid, if needed. Remove from the heat. Crumble the goat cheese with a fork and add it along with the Parmigiano-Reggiano. Add a bit more of the cooking liquid if needed and serve.