In a 6 quart stockpot, heat butter over medium heat. Add celery, carrots, green pepper, and onion; cook and stir 3-4 minutes or until onion is tender. Stir in the flour, curry powder, salt and pepper until blended.
Gradually stir in milk. Add broth, potatoes and corn; bring to a boil. Reduce heat; simmer, covered, 15-20 minutes or until potatoes are tender.
Stir in cheese until melted; remove from heat. Puree heat using an immersion blender. Or, cool slightly and puree in batches in a blender; return to pot and heat through. Stir in parsley.