Heat the olive oil in a large pot or Dutch oven over medium heat. Add the sliced sausage and cook until lightly browned, about 3 to 4 minutes. Remove the sausage and set it aside.
Add the chopped onion and bell pepper to the same pot. Cook until softened, about 5 minutes.
Stir in the minced garlic and Cajun seasoning. Cook for 1 minute until fragrant.
Pour in the undrained diced tomatoes and chicken broth. Bring the mixture to a boil.
Add the dry pasta to the boiling liquid. Stir well to prevent sticking. Reduce the heat to medium-low, cover the pot, and simmer for 12 to 15 minutes, or until the pasta is cooked al dente and most of the liquid is absorbed. Stir occasionally during cooking.
Stir in the heavy cream and the cooked sausage. Heat through for 2 minutes, but do not boil after adding the cream.
Remove the pot from the heat. Stir in the grated Parmesan cheese until the sauce is smooth and creamy.
Serve immediately, garnished with fresh parsley.
Notes
For extra heat, add 1/4 teaspoon of cayenne pepper with the Cajun seasoning.
If the sauce seems too thick, add a splash more broth or milk when stirring in the cream.
You can substitute chicken or shrimp for the sausage if desired.