Heat the butter in a 10-inch saute pan set over medium heat. Once melted, add the celery, salt, and pepper, and cook until the celery begins to soften slightly, approximately 5 minutes. Add the beef broth and stir to combine. Cover and reduce the heat to low. Cook until the celery is tender but not mushy, approximately 5 minutes. Uncover and allow the celery to continue to cook for an additional 5 minutes or until the liquid has been reduced to a glaze. Transfer to a serving dish and garnish with the reserved celery leaves.