Combine the ingredients for the Cajun seasoning in a small bowl.
Cut the chicken into ½ to ¾-inch cubes. Place the cubed chicken in a bowl, pour the Cajun seasoning over top, and stir to coat the chicken in spices.
Add the olive oil and butter to a large deep skillet. Heat them over medium-high until the skillet is hot and butter is melted and foamy. Add the seasoned chicken and cook a couple minutes on each side, just until browned.
Add the diced yellow onion to the skillet and sauté for about 2 minutes until the onion begins to soften and deglaze the pan.
Add the pasta, fire roasted diced tomatoes (with juices), and chicken broth to the skillet. Stir to combine.
Place a lid on the skillet and bring to a boil. Once boiling, reduce heat to medium-low and simmer for about 10 minutes, stirring every couple of minutes until the pasta is tender and the liquid is thick and saucy.
Add the cream cheese in chunks and stir until it melts completely into the sauce.