Heat butter in saucepan. Add onions and celery and cook until tender. Add broth, black pepper and potatoes. Heat to a boil. Cover and cook over low heat 15 minutes or until potatoes are tender. Place half the broth mixture and half the milk in blender or food processor.
Place the bacon in a large, deep skillet, and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain the bacon slices on a paper towel-lined plate, crumble, and set aside. Cook and stir onion and celery in the remaining bacon