Preheat oven to 350 degrees F (175 degrees C). Spray a 9x13-inch baking dish with cooking spray.

Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally until cooked through but firm to the bite, 8 minutes. Drain.

Stir sour cream and cream cheese together in a bowl until smooth; add evaporated milk. Stir Buffalo wing sauce and ranch dressing into sour cream mixture; mix in shredded chicken, macaroni, and 1 1/2 cups Cheddar cheese. Pour macaroni mixture into prepared baking dish. Top with bread crumbs and remaining 1/2 cup Cheddar cheese; drizzle melted butter over the top.

Bake in the preheated oven until bubbling and golden, 20 to 30 minutes.