Cut chicken breasts in half lengthwise. Cut each half into strips. Cut strips into bite size pieces. Season with salt, black pepper, and cajun seasoning. Mix well to coat.
Add 4 TBS avocado oil to a large Dutch oven or large pot and heat over medium high. Add in 1/2 of the chicken in a one layer and cook for 2-3 minutes until seared. Turn chicken over and cook an additional 2-3 minutes until seared. Remove chicken to a plate and set aside. Cook 2nd batch of chicken and remove to plate.NOTE: Chicken does not need to be cooked all the way through, just seared or lightly browned.
Add minced garlic into Dutch oven and cook for 30 seconds over medium heat. Add the seared chicken back into Dutch oven and stir into garlic. Add in minced onion and stir for 30 seconds.
Stir in 1 tsp cajun seasoning, 1/4 tsp salt, and 1/8 tsp black pepper. Stir in 4 cups chicken broth and 2 1/2 cups heavy whipping cream. Bring to a boil over high heat.
Once it's boiling add in 1 lb cry uncooked pasta (I used rigatoni) and stir. Try to submerge pasta into liquid.
Turn down heat to a low. Cover pot with a lid. Cook for 15-20 minutes until pasta is tender.NOTE: remove lid every few minutes to stir ingredients to keep from sticking on bottom of pot.
Turn off the burner and add 2 cups shredded parmesan cheese. Stir well to combine. Garnish with parsley.