Melt butter in a Dutch oven over medium heat. Add onion, celery, and garlic; sauté 10 minutes or until tender. Add broth, potato, and chopped rosemary. Bring to a boil; cover, reduce heat, and simmer 25 minutes or until potato is very tender. Meanwhile, heat a large nonstick skillet over medium-high heat. Add ham, and cook until browned and crisp on all sides. Remove from heat; set aside.

Process potato mixture, in batches, in a food processor or blender until smooth. Return to Dutch oven; stir in peanut butter. Cook over medium-low heat until smooth, stirring often. Stir in cream, salt, and pepper; cook until thoroughly heated.To serve, ladle into individual bowls.

Top each serving with ham. Garnish, if desired.