Preparation of Ingredients: Assemble all necessary ingredients to ensure that they are readily accessible for the cooking process.
Preheating and Mixture Preparation: Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). In a 9x13-inch baking dish, combine the shredded chicken, cream of chicken soup, scallions, sour cream, chicken broth, Dijon mustard, garlic powder, onion powder, black pepper, and salt. Distribute this mixture evenly across the base of the dish.
Preparing the Topping: In a separate mixing bowl, blend the crushed crackers with the melted butter until each piece is uniformly coated. Evenly distribute this cracker mixture over the surface of the chicken base.
Baking: Place the dish in the preheated oven and bake until the casserole is bubbling and the cracker topping has achieved a golden brown coloration, which typically takes about 30 minutes.
Garnishing and Serving: Once removed from the oven, enhance the dish’s appearance and flavor by garnishing with additional sliced scallions. Serve while hot for optimal enjoyment.