Preheat your oven to 350°F (175°C) and spray a 9x9 casserole dish with cooking spray.

Drain canned green beans or blanch fresh green beans in boiling water for 2 minutes and transfer to ice bath.

In a mixing bowl, combine the cream of mushroom soup with milk and whisk until smooth. Stir in soy sauce.

Fold prepared green beans into the mushroom sauce, add two-thirds of the crispy fried onions and season with black pepper.

For air fryer, pour mixture into the dish and air fry at 350°F for 10 minutes. Stir and top with remaining onions, air fry for another 2-3 minutes.

For oven, bake for 25 minutes, stir and top with remaining onions, return for 5 minutes until golden brown.

Let the casserole sit for 5 minutes before serving to allow the flavors to meld.