You may note that traditionally, a condensed soup is used. However, I find that using the ready to eat soup provides a better result and the quality is better. DO NOT ADD MILK to this recipe! The soup is prefect as it is. I prefer the progresso as the mushrooms are bigger, but if you have another brand you prefer, that is perfect as well... You can do it completely from scratch, by seasoning approx. 1.5 cups of cream broth and slow cooking mushrooms in it. If you prefer your casserole thicker, you can use more fried onions.
In a medium bowl, mix the green beans of your choosing (see options) with the ready-to-eat soup.
Fold into the mix 3/4 can of fried onions
Add mix to casserole dish
Here you have a choice - you can either top with onions now, or wait until 10 minutes remain to add the onions. While adding now is easiest, adding with 10 minutes remaining provides the crispiest results!