Preheat the oven to 350°F (175°C).
In a skillet, brown the ground beef over medium heat until fully cooked.
Add the chopped onion and cook until translucent.
In a large baking dish, layer the sliced potatoes, followed by the cooked beef and onion mixture.
Add the mixed vegetables on top of the beef.
Pour the cream of mushroom soup over the entire dish.
Cover with aluminum foil and bake for 1 hour.
Remove the foil, sprinkle cheddar cheese on top, and bake for an additional 15 minutes until the cheese is melted and bubbly.