Preheat oven to 375°F
Coat 9-inch square baking dish with non-stick cooking spray. Set aside.
Bring a large pot of water to a boil. Cook macaroni for 2 minutes less than package directions. Drain and set aside. Reserve pot for later.
While pasta cooks, cut squash in half and scoop out seeds. Cut into large chunks. Place in microwave-safe bowl with water. Cover with plastic wrap. Microwave on high until tender. about 10 minutes. Let cool .
While squash cooks and cools, grate cheddar cheese.
Peel cooled squash. Place in pot used to cook pasta. Mash with a fork. Add cottage cheese and milk. Stir until smooth. Add pasta, cheddar cheese, salt, and pepper. Stir until combined. Spread evenly in prepared baking dish. Sprinkle with breadcrumbs
Bake until breadcrumbs are browned and the edges are bubbling, about 45 minutes