Preheat your oven to 350°F. Prepare a 9x9-inch baking dish by lightly coating it with cooking spray.
In a large mixing bowl, combine the chopped chicken, ranch seasoning mix, shredded cheddar cheese, chopped bacon, sour cream, and cream of chicken soup. Stir until all ingredients are well mixed.
Transfer the chicken mixture to the prepared baking dish, spreading it out evenly.
In a small bowl, mix together the crushed crackers and melted butter until the crackers are evenly moistened. Sprinkle this mixture over the top of the chicken layer in the baking dish.
Place the baking dish in the preheated oven and bake uncovered for 30 to 40 minutes, or until the casserole is bubbly and the topping is golden brown.