Preheat the oven to 350°F (175°C).

In a skillet, brown the ground beef and onion until the meat is cooked through. Drain the excess fat.

In a large bowl, combine the shredded potatoes, cream of mushroom soup, milk, cheese, salt, and pepper.

Add the cooked beef and onion mixture to the potato mixture and stir until well combined.

Pour the mixture into a baking dish and spread evenly.

Bake in the preheated oven for 45-50 minutes or until the top is golden and bubbly.