Cook the pasta and spinach: Bring a large pot of salted water to a boil. Cook 12 ounces short pasta according to the package directions. Halfway through cooking, add 10 ounces spinach to the same pot. Cook until the pasta is al dente and the spinach is wilted.
Make the ricotta sauce: While the pasta cooks, whisk together 1 cup ricotta, ½ cup grated Parmesan, 1 tablespoon extra virgin olive oil, 1 teaspoon lemon zest, ⅛ teaspoon grated nutmeg, ¾ teaspoon salt, pep¼ teaspoon black pepper, and ½ cup of hot pasta water in a large bowl until smooth and creamy.
Toss and serve: Before draining, reserve about 1 cup of the pasta water. Drain the pasta and spinach, then add them to the bowl with the sauce. Toss well, adding more pasta water a little at a time until the sauce is creamy and coats the pasta. Serve right away with extra Parmesan, black pepper, and lemon zest if you like.
Substitutions
Rigatoni → Penne, fusilli, farfalle, shells, spaghetti, or your favorite gluten-free pasta.