Add 2 tablespoons olive oil to the pan, return to medium heat, then add the onion, garlic, sage, and red pepper flakes. Cook this about 8-10 minutes, until the onion and garlic start to brown. Return the sausage to the pan and heat through.
While the sauce is cooking, bring a large pot of salted water to a boil over high heat. Add the pasta and cook according to the instructions of the package. Drain.
When the sauce is ready, add the drained pasta to the sauce and cook over medium heat for 3 to 5 minutes, stirring constantly. Remove from heat and stir in the Parmesan cheese.
Recipe by Webicurean at http://blog.webicurean.com/2013/09/22/penne-spicy-pumpkin-sausage-sauce-sundaysupper/