Season chicken breasts with Cajun spice, oregano, paprika, and salt. Heat butter in a cast iron pan, then sear the chicken for 3–5 minutes per side until golden and cooked through. Remove and set aside, then dice or shred once cooled.
In a large pot, heat some oil and add chopped onions. Sauté until soft, then stir in minced garlic and cook until fragrant.
Add canned tomatoes, chicken stock, and water. Stir well, then add the pasta. Cover and cook for 8–10 minutes until the pasta is al dente.
Stir in cream cheese until melted, then add heavy cream, chicken, and grated Parmesan. Lower the heat and let it simmer for about 5 minutes so the flavors blend. Adjust seasoning with salt and pepper if needed.
Turn off the heat, add freshly chopped coriander, stir gently, and serve warm.