Preheat oven to 425°F and adjust the oven rack to the middle position. Spray a 9x13-inch casserole dish with nonstick cooking spray.
In a large Dutch oven, bring 4 quarts of water to boil.
Add 2 tablespoons table salt and the prepared beans, stir, and cook the beans until barely crisp or soft (depending on personal preference), 7-10 minutes.
2 pounds fresh green beans, 2 tablespoons table salt
While the beans cook, fill a large bowl with ice water and set aside.
When the beans are ready, drain them in a colander and immediately plunge them into ice water to stop cooking.
Once the beans have cooled, spread them over paper towels and pat them to dry.
In a large bowl, combine the mushroom soup, milk, soy sauce, cheddar cheese, and 1 cup of crushed fried onions.
21 ounces cream of mushroom soup, ¾ cup milk, 1 teaspoon low-sodium soy sauce, 2 cups freshly shredded cheddar cheese, 6 ounces crispy fried onions
Add the beans and stir to coat evenly. Season the bean/soup mixture with kosher salt and freshly ground black pepper to taste.
Kosher salt and freshly ground black pepper
Pour the green beans into the prepared dish.
Bake 20 minutes at 425°F.
Remove the beans from the oven, and reduce oven temperature to 350°F.
Sprinkle the top of the beans, with the remaining 2 cups of fried onions and bake an additional 20-25 minutes or until the top is golden brown and the casserole is bubbly.