1. Gather all the ingredients: green beans (canned, frozen, or fresh), cream of mushroom soup, milk, soy sauce, and French fried onions. For fresh green beans, trim and blanch them until tender before use.
2. Preheat your oven to 350°F (175°C) to ensure it’s ready for baking the casserole.
3. In a large mixing bowl, combine two cans of cream of mushroom soup, one cup of milk, and two tablespoons of soy sauce. Stir the mixture until it is smooth and evenly blended.
4. Add the green beans to the bowl and fold them into the soup mixture, making sure they are evenly coated.
5. Transfer the green bean and soup mixture into a shallow baking dish, spreading it evenly for consistent cooking.
6. Sprinkle one cup of French fried onions over the top of the casserole to create a crunchy topping. Reserve the remaining 1/3 cup for later use.
7. Place the baking dish into the preheated oven and bake for 30 minutes to allow the casserole to heat thoroughly and the flavors to combine.
8. After 30 minutes, remove the casserole from the oven and sprinkle the reserved 1/3 cup of French fried onions over the top.
9. Return the casserole to the oven and bake for an additional 5-10 minutes, or until the onions are golden brown and crispy.
10. Remove the casserole from the oven and let it cool slightly.
11. Serve the Green Bean Casserole warm as a side dish, pairing it with main courses or other holiday favorites. Enjoy!