In alarge soup pot over medium high heat, saute the mushrooms, onions, carrots and celery with the ½ cup butter until tender, about 5-7 minutes. Add 2 tsp salt and ½ tsp pepper while veggies are sauteing.
When veggies are tender, start stirring in the flour, adding ¼ cup at a time, mixing well with each addition.
When flour is all added, quickly begin pouring in the chicken stock and water as you stir continuously, adding 1-2 cups at a time.
Once all the chicken stock and water is added, the soup needs to come up to ta boil to thicken. Stir occasionally to make sure nothing is sticking to the bottom of the pan.
When soup has thickened, add the cooked Rice-A-Roni and chicken. Mix well. Then add the can of evaporated milk. Taste soup and adjust salt and pepper, if needed.
If served immediately, the soup will be a perfect creamy consistency. If not served immediately, you made need to add a little bit of milk when you reheat it. Otherwise, it will be a really thick stew-like soup.
Tastes great with bread or rolls.
