Cook the penne pasta in boiling salted water following the package directions; save 1/2 cup of the pasta water and drain.
Meanwhile, crumble the sausage in a large skillet over medium heat; cook for about 5 minutes, stirring constantly. Add the onion and cook for 3 to 4 more minutes, until the onion is translucent. Add the garlic and cook for 1 minute. Stir the flour into the sausage mixture; stir and cook for 2 minutes longer.
Add the sage and wine and cook for 2 minutes, stirring constantly. Stir in the chicken stock and spinach. Cook, until the spinach has wilted.
Stir in the hot cooked penne pasta, cream, and 2/3 cup of Parmesan cheese. Heat through. Add some of the reserved pasta water, if desired.
Taste and add salt and pepper, as needed.
Spoon into a serving dish and top with more grated Parmesan cheese.