In a large skillet, cook 1tablespoon of olive oil over high heat for 2 minutes. Add the sausage and break up into small pieces. Cook sausage until it browns, about 3 minutes. Remove sausage with a slotted spoon and place in a bowl. Set aside. Leave about 1 tablespoon of the oil from the sausage in the skillet. Add the remaining 3 tablespoons of olive oil. Add the onion, garlic and chopped sage. Cook for approximately 10 minutes, stirring well until the onion and garlic begin to brown. Add 1/4 teaspoon of red pepper flakes if desired. Add the reserved sausage back into the skillet with onions and garlic and cook for 2 more minutes, stirring well. Add the wine and deglaze the pan making sure to scrape the skillet to dislodge all the browned bits. Cook for 8 minutes. Add the pumpkin puree and cook for 2 minutes, stirring well. Add the chicken stock and cinnamon. Bring to a boil over high heat, then reduce heat and simmer for 30 minutes. While sauce is cooking, bring a large pot of water (add 2 tablespoons of salt) to a boil. Add the pasta and cook according to package instructions. Drain the pasta and pour back into the pot. Add the sauce and cook over medium heat for 3 to 5 minutes, gently stirring to incorporate. Add the optional Parmesan cheese and serve. Garnish with shaved Parmesan cheese. Serves 6 to 8.