Preheat your oven to 350°F and lightly grease a 9x13-inch baking dish with butter or cooking spray.

In a large mixing bowl, combine the shredded chicken, cream of chicken soup, and sour cream, stirring until everything is well incorporated and the mixture looks smooth and creamy.

Spread the chicken mixture into your prepared baking dish, using a spatula to smooth it into an even layer that reaches all the corners.

Place the crackers in a resealable bag and crush them with a rolling pin or the bottom of a measuring cup until you have a mix of fine crumbs and some larger pieces.

Transfer the crushed crackers to a medium bowl and pour the melted butter over them, stirring with a fork until all the crumbs are coated with butter.

Sprinkle the buttery cracker mixture evenly over the chicken layer, distributing it all the way to the edges of the dish.

Bake for 30-35 minutes, until the filling is bubbling around the edges and the cracker topping has turned golden brown.

Remove from the oven and let the casserole rest for about 5 minutes before serving.