Cheesy Hamburger Potato Casserole

Ingredients:

1 lb ground beef
4 medium potatoes, peeled and thinly sliced
1 small onion, chopped
1 can (10.5 oz) cream of mushroom soup
1 cup sour cream
1 1/2 cups shredded cheddar cheese
1/2 tsp garlic powder
1/2 tsp onion powder
Salt and pepper to taste
1 tbsp olive oil (for cooking)
1/2 cup milk
1/2 cup shredded mozzarella cheese (optional, for topping)
Preparation:
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