Combine main ingredients in large pot, bring to boil; lower to a simmer and stir occassionally.

Melt butter in saucepan, whisk flour into melted butter, then slowly whisk milk into butter/flour mixture in saucepan. Stir constantly until thick.

After 45 mins, or when potatoes are soft, add milk mixture. Remove from heat.

Garnish with cheddar cheese and green onions.