Preheat oven to 350°F. Combine soup and milk in 1-1/2 quart baking dish. Stir in beans, mushrooms and 2/3 cup French fried onions.
Bake 25 minutes or until the bean mixture is hot and bubbling. Stir then sprinkle with the remaining onions.
Bake 5 minutes or until onions are golden brown.