In a large saucepan, melt butter over medium heat. Add onion and cook until tender. Add chicken broth, celery, 2 potatoes which have been pared and sliced; add parsley. Cover and simmer for 30 minutes.

Pour all cooked ingredients into electric blender. Cover and process until smooth. Return puree to pan.

Pare remaining 2 potatoes and dice. Add to kettle along with remaining ingredients. Simmer, covered for 20 minutes or until potatoes are tender. Makes 6 servings.