Pat the chicken breasts dry and season evenly on all sides with Cajun seasoning, salt, and black pepper.
Heat the oil in a large pot over medium heat and sear the chicken for 4–5 minutes per side until golden. Remove and set aside to rest.
Add butter to the same pot, then sauté the onion, bell pepper, and jalapeño for 3–4 minutes until softened, scraping up browned bits.
Pour in the chicken broth and stir well to deglaze the pot. Bring to a gentle simmer.
Stir in garlic powder, remaining Cajun seasoning, and half-and-half. Lower the heat and do not boil.
Shred or cube the rested chicken and return it to the pot along with crushed tomatoes if using.
Simmer gently for 5–10 minutes, then taste and adjust seasoning or heat with hot sauce if needed.
Remove from heat and garnish with fresh parsley before serving.