In a 3-qt. saucepan, brown beef over medium-high heat; drain and set aside.
In the same saucepan over medium heat, saute onion, carrots, celery, basil and parsley in 1 tablespoon butter until vegetables are tender, about 10 minutes. Press garlic into pot, and cook until just fragrant, about 1 minute.
Add broth, potatoes and beef; bring to a boil. Reduce heat; cover and simmer for 10-12 minutes or until potatoes are tender.
Meanwhile, in a small skillet, melt remaining butter. Add flour; cook and stir for 3-5 minutes or until bubbly. Add to soup; bring to a boil. Cook and stir for 2 minutes.
Reduce heat to low. Add cheese, milk, salt and pepper; cook and stir until cheese melts. Remove from the heat; blend in sour cream.