Sprinkle salt into a large pot of water; bring to a boil. Cook elbow macaroni in the boiling water, stirring occasionally until tender yet firm to the bite, about 8 minutes. Drain. Preheat oven to 350 degrees F (175 degrees C). Grease a 4-quart baking dish with cooking spray. Pour hot macaroni into the baking dish. Add butter; stir until melted. Whisk evaporated milk, milk, eggs, and sour cream together in a large bowl. Season with sugar, pepper, and salt. Sprinkle Colby Jack cheese, processed cheese food, and Cheddar cheese over macaroni. Pour milk mixture on top. Bake in the preheated oven until top is lightly browned, 30 to 45 minutes.