Preheat oven to 350° Fahrenheit. Lightly spray 9x13 baking dish with neutral-flavored cooking spray, making sure to coat bottom and inner sides of dish.
Spread 3-5 cups shredded rotisserie chicken evenly across baking dish, covering bottom of dish completely. Sprinkle preferred amounts of salt and freshly ground black pepper over shredded chicken.
Add 1 10.5-ounce can condensed cream of chicken soup, 1 10.5-ounce can condensed cream of mushroom soup, 1 teaspoon garlic powder, 1 cup milk, salt, and plenty of freshly ground black pepper to first medium mixing bowl. Stir all ingredients together until fully combined.
Transfer soup mixture to baking dish, spreading soup mixture evenly over layer of rotisserie chicken.
Spread 1 12-ounce bag frozen green beans evenly across soup layer.
Add 1 8-ounce package savory herb-seasoned stuffing mix, ½ cup melted unsalted butter, ½ cup water, and ¼ cup dried cranberries to second medium mixing bowl. Stir ingredients together until incorporated and well blended.
Spread stuffing mixture across top of green bean layer, covering green beans evenly.
Place baking dish in preheated oven. Bake casserole 20 to 30 minutes, uncovered, or until bubbling. Stuffing layer should be moist and all layers cooked through.
When casserole is fully baked, carefully remove baking dish from oven. Gently fluff stuffing layer with fork, then serve casserole warm with desired sides.