Slice your chicken into bite-sized strips or chunks and then coat the pieces well with Cajun seasoning.
Heat a large sauté pan or skillet, with sides at least - inches high, over med-high heat. Once the pan is hot, add the oil.
Once oil is hot and begins to shimmer, add the seasoned chicken and sauté for 4 minutes or so. Just enough to brown all sides of the chicken. Add additional oil if necessary.
Remove chicken to a bowl, and add in onion, adding additional oil if necessary), sauté for 2 minutes, add in garlic or garlic paste and sauté another 1-2 minutes, stirring often.
Remove onion mixture and put it in the bowl with the chicken, cover.
Add in vegetable or chicken broth to the pan, turn heat to high, and stir it around detaching any browned bits or seasoning from the pan.
As soon as broth begins to boil, add in noodles.
Allow noodles to cook, stirring often for 6 minutes. Lower heat to medium and add in creamed cheese. Stir in until creamy.
Add in heavy cream, tomatoes and your chicken & onion mixture, stirring to incorporate.
Add in another ½ TBS to 1 TBS of Cajun seasoning.
Transfer contents to a casserole dish (or if your pan is oven safe, feel free to use that as well).
Bake in a preheated oven at 350 degrees for 15-20 minutes.
Taste and adjust seasoning.
Sprinkle with additional Cajun seasoning (if desired), snipped parsley and or sliced scallions.