Preheat the Oven
Preheat your oven to 350°F (175°C).
Prepare the Green Beans
If using fresh green beans, blanch them by boiling in water for 3-5 minutes until they turn bright green. Drain and set aside.
If using canned green beans, drain and rinse them to remove excess salt.
Mix the Casserole Base
In a large mixing bowl, combine the cream of mushroom soup, milk, soy sauce (if using), black pepper, and garlic powder. Stir until well combined.
Combine Green Beans and Sauce
Add the green beans to the mixture and stir until all the beans are evenly coated in the sauce.
Assemble the Casserole
Pour the green bean mixture into a 9x13-inch baking dish. Spread it evenly.
Add the Topping
Sprinkle 1 cup of crispy fried onions on top of the green bean mixture.
Bake the Casserole
Bake in the preheated oven for 25-30 minutes, until the casserole is bubbly and the onions on top are golden brown.
Final Touch
For extra crunch, add the remaining 1/2 cup of fried onions during the last 5 minutes of baking.
Serve and Enjoy
Remove the casserole from the oven and let it sit for a few minutes before serving.