Preheat: Set oven to 350°F (175°C) and grease a 9×13-inch baking dish.
Mix Base: In a large bowl, combine chicken, cream of chicken soup, sour cream, and chicken broth until smooth.
Layer: Spread chicken mixture evenly into prepared dish.
Prepare Stuffing: Make stuffing mix with about 10% less liquid than package calls for to avoid sogginess.
Top & Butter: Spoon stuffing evenly over chicken mixture without pressing down; drizzle with melted butter.
Bake: Bake uncovered for 35–40 minutes until golden brown and bubbling; internal temp should reach 165°F.
Rest & Serve: Let casserole rest 10 minutes before serving for best texture.