Heat olive oil in a large skillet over medium heat.
Add the Italian sausage to the skillet, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes.
Add the diced onion to the skillet and cook until softened, about 3-4 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Pour in the crushed tomatoes and chicken broth, stirring to combine.
Add the rigatoni pasta, dried Italian seasoning, red pepper flakes, salt, and black pepper to the skillet. Stir well to combine all ingredients.
Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 15-18 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Remove the skillet from heat and stir in the grated Parmesan cheese until melted and well combined.
Sprinkle chopped fresh basil over the top before serving.