In a large pot of salted boiling water, add the pasta and cook according to package instructions. Once done, drain the pasta and set it aside.
While the pasta is cooking, begin heating a large deep skillet over medium heat and add the oil. Once the skillet is hot add the Italian sausage and cook until fully brown.
Now add the diced onion, garlic, and spices (Italian seasoning, salt, garlic powder, black pepper, and red chili flakes) Mix to combine with the sausage and cook for 2-3 minutes until the onion is translucent and the garlic is fragrant.
Next reduce the heat to medium-low and stir in the marinara sauce. Then add in the half-and-half and parmesan cheese. Stir until well combined. Simmer the pasta sauce for 3-4 minutes until it starts to thicken slightly.
Add the cooked pasta to the skillet and stir well to combine with the sauce. Serve with fresh chopped parsley (optional), extra parmesan cheese, and some garlic bread. Enjoy!