Cook macaroni according to package directions; drain. Place in a 5-qt. slow cooker; add butter. In a large bowl, mix 3 cups cheese, evaporated milk, condensed soup, 2% milk and eggs. Pour over macaroni mixture; stir to combine. Cook, covered, on low for 3-1/2 to 4 hours or until a thermometer reads at least 160°., Sprinkle with remaining cheese. Cook, covered, on low until cheese is melted, 15-20 minutes longer. Sprinkle with paprika.