Brown the ground beef in a skillet over medium heat.

Add the chopped onion to the skillet and cook until softened.

Season with salt and pepper.

Drain off any excess grease.

Layer the diced potatoes over the meat mixture in a casserole dish.

Add a layer of drained green beans on top of the potatoes.

In a separate saucepan, heat the cream of celery soup and melt in the American cheese until smooth.

Pour the cheese sauce over the casserole.

Cover the casserole dish with a lid or aluminum foil.

Bake in a preheated oven at 350°F (175°C) for 1 to 1.5 hours, or until the potatoes are tender.

Let cool slightly before serving.