In a large saucepan over medium heat, cook and crumble beef until no longer pink, 6-8 minutes; drain and remove from pan. In same saucepan, melt 1 tablespoon butter over medium heat. Saute onion, carrots, celery, basil and parsley until vegetables are tender, about 10 minutes. Add potatoes, broth and ground beef; bring to a boil. Reduce heat; simmer, covered, until potatoes are tender, 10-12 minutes.

Meanwhile, in a small skillet, melt remaining 3 tablespoons butter. Add flour; cook and stir until bubbly, 3-5 minutes. Add to soup; bring to a boil. Cook and stir 2 minutes. Reduce heat to low. Stir in cheese, milk, salt and pepper; cook until cheese melts. Remove from heat; blend in sour cream. If desired, serve with onion rings and green onions.