Hi Kim, Here's the recipe you requested, I found it at TKL's COPYCAT page.

Bennigan's Potato Soup

1 3/4 ounces Ham base -
2 quarts Chicken stock
8 ounces Yellow onion -- dice
3 ounces Margarine
2 pounds Potatoes -- bite size
1 1/2 teaspoons Black pepper
2 cups Milk
3 ounces Flour
3 ounces Margarine

Combine chicken stock in sauce pan with ham base. Stir until lumps are gone. In separate stock pot: melt first margarine measurement; add onion and sautee until transparent. Add potato bite size pieces and pepper. Add chicken stock mix and stir until well mixed. Bring mixture to a boil. In small pan, melt second margarine measure and add flour to create a roux. It should be light brown in color. When stock comes to a boil, add roux with a wire whisk. This will cause the soup to start thickening. Return to a boil.
Slowly add the milk. If the soup is too thin, make additional roux and add it to the soup. If you need to do this, be sure to cook the roux until a tan color.
This will get rid of the raw flour taste. If the soup is too thick, thin it out with more milk.