Preheat the oven to 350°F (175°C).
Drain and rinse the green beans, then set aside.
In a large mixing bowl, combine the cream of mushroom soup, milk, and soy sauce. Stir until smooth, then add garlic powder, black pepper, and salt.
Fold the green beans into the creamy sauce and pour into a greased 9x13-inch baking dish. If using, sprinkle shredded cheddar cheese on top.
Bake for 25 minutes, then stir in half of the French fried onions. Top with remaining onions and return to the oven for an additional 10-15 minutes until golden brown and bubbly.
Let cool for a few minutes before serving.