Blanch green beans for about. 5 minutes in boiling water. Remove, drain and move to side.
In a sauce pan add oil to pan and bring to medium-heat. Saute onions for approx 4 minutes. Add mushrooms and saute 5 more minutes or until onions are translucent and mushrooms are soft. Add minced garlic and stir for 1 minute. Pour in stock and heat thoroughly.
Slowly add in flour, stirring to keep in mixing in. Add salt and pepper to taste. Once your creamy sauce is of desired consistency, add green beans, mix and serve warm topped with your favorite topping.
Of course, you can also save time by using a canned cream of mushroom soup 😉