Heat the oil in a large saucepan over medium heat, then add the chopped onion and allow it to soften in the oil. Remove the sausage casing, then crumble the sausage adding to the pan. Allow the sausage to brown with the onion.
Once the sausage is nicely browned, add the white wine and the tomato sauce. Add the red pepper flakes (if using) then cook the sauce for about ten minutes to allow the flavors to blend and the sauce to thicken.
Cook the pasta according to the package directions then add the pasta right into the saucepan. Reserve a little cooking water to thin the sauce as needed.
Continue to heat the pasta with the sauce for about two minutes. Top the pasta with the Parmesan cheese then serve. Pass additional cheese at the table.