Prep the base: Add the diced onion, sliced bell peppers, and canned diced tomatoes (with juices) to the slow cooker.
Pour in the chicken broth.
Season the chicken: Pat the chicken dry and sprinkle both sides with Cajun seasoning, salt, and pepper. Place the chicken on top of the vegetables.
Add aromatics: Sprinkle in the minced garlic. If using butter, add it now for a richer sauce.
Cook low and slow: Cover and cook on Low for 4–5 hours or High for 2.5–3 hours, until the chicken is tender and easily shreds or slices.
Make it creamy: About 30 minutes before serving, add the cubed cream cheese and heavy cream.
Stir gently to help it melt into the sauce. If the sauce looks thin, whisk 1–2 teaspoons cornstarch with a splash of cold water and stir it in.
Adjust seasoning: Taste and add more Cajun seasoning, salt, or pepper if needed. For extra heat, add a pinch of cayenne.
Shred or slice: Remove the chicken, shred or slice it, then return it to the sauce and stir to coat.
Serve: Spoon the creamy Cajun chicken over rice, pasta, or mashed potatoes.
Garnish with chopped parsley or green onions.