Grease the slow cooker lightly or mist with cooking spray.
Whisk the condensed soup, milk, soy sauce, garlic powder, onion powder, salt, and pepper in a large bowl.
Fold in the green beans, cheddar, and 1 cup fried onions until evenly coated.
Spread the mixture into the slow cooker and smooth the top.
Cover and cook on Low for about 2 hours 20 minutes, until hot and bubbling at the edges.
Scatter the remaining fried onions on top. Cover and cook 10 minutes more to warm the topping.