In a large saucepan, melt butter over medium heat. Add onion, green pepper and celery; cook until vegetables are tender. Stir in milk, corn, broth, soup, cheese product, shredded cheese, oregano and black pepper.
Cook, uncovered, over medium heat about 15 minutes, or until mixture is almost simmering (do not boil), stirring occasionally. Makes 6 to 8 main-dish servings.