In a large skillet, over medium high heat, brown sausage and onion together for 5 minutes; until sausage is browned and onions are tender. Add garlic and cook for 1 minute until fragrant.
Add pasta, chicken broth, heavy cream, milk, parmesan cheese, and Cajun seasoning to the pan. Stir until well combined.
Bring to a boil, cover and reduce to a simmer. Cook for 10 minutes until the pasta is cooked, stirring occasionally.
Adjust the Cajun seasoning to your desired heat level.