In large covered saucepan cook cauliflower in chicken broth till almost tender, about 10 minutes.
Do not drain; set aside.
In bowl gradually add milk to soup; mix well.
Slowly blend 1/4 cup cold water into cornstarch and white pepper; stir into soup mixture.
Pour soup mixture over cauliflower; cook and stir till thickened and bubbly.
Stir in ham; simmer till hot, about 10 minutes.
Garnish with sliced green onion with tops, if desired.