Bring a large pot of water to a boil. Add about 1 tablespoon salt, then add the pasta and cook according to package directions until al dente. Drain well.
1 lb. pasta
Meanwhile, heat oil in a large skillet over medium-high heat. Sauté the chopped onions in the oil for 3-5 minutes until softened. Add minced garlic and saute for another 30-60 seconds until fragrant.
2 Tablespoons olive oil, 1 medium onion, 4 cloves garlic
Add Italian sausage to the onions, breaking it up with a wooden spoon while it cooks to create crumbles. Cook for about 5 minutes until browned.
1 lb. mild or sweet Italian sausage
Add chicken broth to the sausage and onions, scraping the bottom of the pan to release any browned bits before adding the Italian seasoning, black pepper, and bay leaves.
3/4 cup chicken broth, 1 teaspoon Italian seasoning, 1/4 teaspoon freshly ground black pepper, 2 bay leaves
Add heavy cream and reduce the heat to medium-low. Bring to a simmer, then continue to cook for 10 minutes to allow the flavors to meld and the sauce to reduce slightly.
1 1/2 cups heavy cream
Remove from heat and stir in the Parmesan cheese and fresh basil. Add cooked pasta and stir well to coat with the sauce. Taste and adjust with more Parmesan, salt & pepper, or basil as desired. Let sit for 5 minutes before stirring again and serving.
1 cup freshly grated Parmesan cheese, 1-2 handfuls fresh basil leaves