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 together macaroni, shredded Cheddar cheese, cottage cheese, sour cream, Parmesan cheese, and salt and pepper in a 9x13-inch baking dish. Mix together bread crumbs and melted butter in a small bowl; sprinkle topping over macaroni mixture.
Bake until top is golden in the preheated oven, 30 to 35 minutes.
