Cheesey Green Bean Casserole

We are having some friends over for dinner tonight. They are bringing a rotisserie chicken and dessert. I needed a fruit and veggie. Since it is citrus season, I fixed grapefruit for our fruit. I had a hard time deciding what vegetable to make. I wanted something a little different. Then I remembered this recipe my mom gave me. It has been almost a year since I last made it. I really should make it more often, it is so good. It's a little more work than your traditional 'campbells' green bean casserole, but totally worth it.

This recipe has butter listed twice - that's because it is used at two different times during preparation.

1/3 cup butter
1/2 cup finely chopped onion
2 (4 oz) cans sliced mushrooms - drained, but save the liquid
1 (5 oz) can water chestnuts, drained and sliced
2 pkgs. frozen French cut green beans, thawed
3 tblsp butter
1/3 cup flour
1 tsp salt
1/2 tsp pepper
1/2 cup mushroom liquid (saved above)
1 cup milk
2 cups shredded cheese (I think I used mild chedder - you could probably use Velveeta)
2 tsp soy sauce
1/2 tsp Tabasco sauce (optional)
1 can French fried onions

Saute raw onions, mushrooms and water chestnuts in 1/3 cup butter until onions are tender. Stir in beans and set aside.
Make cream sauce with the 3 tblsp butter, flour, spices and liquids. Add cheese and sauces. Stir till cheese melts. Put half of bean mixture in baking dish, cover with half of cream sauce, then add remaining beans and cover with remaining sauce. Bake in 350 degree oven for 30 to 45 minutes. Remove from oven and sprinkle one can French fried onions at top and bake ten minutes longer.