Green Bean Casserole
from http://www.foodtimeline.org/foodfaq.html#casseroles

Green Bean Casserole (aka Green Bean Bake)
According to the food historians, the "classic" green bean casserole recipe many Americans remember was a mid-'50s brainchild of the Campbell Soup Company (Camden, NJ). It was a perfect marriage of product promotion (condensed mushroom soup, frozen/canned vegetables), extant culinary traditions (many housewives already served green beans in sauce), economic reality (inexpensive, belly-filling, easily assembled foods) and social craving (creamy, rich comfort dishes). Campbell's didn't "invent" green bean casserole. They capitalized on it.

Culinary evidence confirms vegetables served with cream sauce were consumed in Medieval Europe. Recipes evolved according to local taste and custom. They were introduced to our country by the people who settled here and adapted according to technological advancement and public sentiment. American cookbooks printed in the 19th/early 20th centuries often contained recipes combining green beans and other vegetables (fresh, canned, frozen) with creamy sauces (sour cream, heavy cream, grated cheese, salad dressings, soups). Some were baked (en casserole). Many included other vegetables (mushrooms, onions, peppers) and were topped with crisped carbohydrates (breadcrumbs, toasted onions).

Modern American green bean casserole is a lesson in heritage and enterprise. Stir the collective melting pot and sample what bubbles up.

Also see Copycat French’s Crispy Onion Rings

"Classic" Green Bean casserole
"Campbell's Soup home economists created this recipe in 1955, and it's been popular ever since. For many reasons, explains the headnote accompanying the recipe in Campbell's Best-Every Recipes, 125 Anniversary Edition (1994): "It's delicious and easy to make, easy to remember and leaves room for creativity."

"1 (10 3/4 -ounce ) can condensed cream of mushroom soup
1/2 cup milk
1 teaspoon soy sauce
Pinch black pepper
2 (9-ounce) packages frozen green beans, cooked and drained, or 2 (1-pound) cans green beans, drained.
1 (2.8-ounce) canned French fried onions.

1. Preheat oven to 350 degrees F. Lighly butter 1 1/2-quart casserole.
2. Mix soup, milk, soy sauce, and pepper in casserole. Stir in beans and half the onions.
3. Bake, uncovered, 25 minutes until bubbling; stir well.
4. Top with remaining onions, bake 5 minutes more, and serve."
---The American Century Cookbook: The Most Popular Recipes of the 20th Century, Jean Anderson [Clarkson Potter:New York] 1997 (p. 162)

The oldest recipe we have for Campbell's GBC is this

[1968]
Party-Size Green Bean Casserole
3 cans (10 1/2 ounces each) condensed cream of mushroom soup
1/2 cup milk
1 tablespoon soy sauce
1/4 teaspoon pepper
9 cups cooked French style breen beans (or six 9-ounce packages frozen, or six 1-pound cans, drained)
3 cans (3 1/2 ounces each) French fried onions

Combine soup, milk, soy sauce, pepper; stir until smooth. Mix in beans, 1 1/2 cans onions. Spoon into two 1 1/2 quart casseroles. Bake at 350 degrees F. for 30 minutes or until bubbling. Top with remaining onions. Bake 5 minutes more. 20 servings, 1/2 cup each."
---Easy Ways to Delicious Meals, Campbell Company [Campbell:Camden NJ] rewvised edition, 1968 (p. 186)