Preheat the oven to 350°F (175°C).
In a mixing bowl, combine the cream of mushroom soup, milk, black pepper, and 2/3 cup of French fried onions.
Add the drained green beans and stir to coat evenly.
Transfer the mixture into a 1½-quart baking dish and spread it out evenly.
Bake uncovered for 25 minutes.
Remove from oven, stir, and sprinkle the remaining onions on top.
Return to oven and bake for an additional 5 minutes or until the onions are golden brown.