Place the chopped chicken breast cubes into a large bowl and toss well with the cajun seasoning, until coated.
In a large stockpot or dutch oven, heat the cooking oil over medium heat just until shimmering but not smoking.
Add the chicken, making sure to scrape in the extra seasoning, and sear briefly on all sides, about 2-3 minutes.
Add in the onion, bell pepper and minced garlic and saute for 1-2 minutes until fragrant.
Pour in the chicken broth and fire roasted tomatoes and then bring to a boil.
Once boiling, add in the pasta and simmer for 9-11 minutes or until the pasta reaches your desired texture. Be sure to stir frequently so that the pasta doesn’t stick together.
Remove 1 Tablespoon of the hot liquid and mix it with the cornstarch to make a thick slurry. Mix the cornstarch slurry back into the pan and simmer for 1 minute.
Turn off the heat and gradually stir in the heavy cream.
Remove from the heat and allow the pasta to cool and thicken for 5 minutes.
Garnish with chopped green onions or fresh chopped parsley, optional and serve warm.