In 3-quart saucepan, melt butter over medium heat. Add celery; cook 2 to 3 minutes, stirring frequently, until crisp-tender.
Stir in flour and pepper until well blended. Increase heat to medium-high; gradually stir in broth, cooking and stirring until bubbly and thickened.
Stir in potatoes, turkey breast, peas and milk. Heat to boiling. Reduce heat to low; cover and simmer 8 to 10 minutes, stirring occasionally, until potatoes are tender. During last 2 minutes of cooking time, stir in parsley.