Melt butter in saucepan over medium heat.
Add onion and
celery and
saute 5 minutes until
soft but not brown.
Add chicken broth, potatoes, corn sugar, salt and pepper.
Cover and simmer until potatoes are barely tender, about 30 minutes.
Whisk flour into 1 cup half and half. Stir into soup. Add remaining half and half and simmer until soup has thickened to creamy consistency, about 15 minutes. Season to taste with additional salt and pepper if needed. If too thick, add
a little milk; if too thin, simmer 5 to 10 minutes more