Melt butter in large saucepan over medium heat. Add onion; cook 2 to 3 minutes or until crisp-tender, stirring frequently.
Add all remaining ingredients except cheese. Bring to a boil. Reduce heat; cover and simmer 8 to 10 minutes or until potatoes and vegetables are tender.
Add cheese; cook over medium-low heat until cheese is melted and smooth, and soup is thoroughly heated, stirring occasionally.