Creating Hamburger Potato Casserole is simpler than you might think! Just follow these easy steps:

1. Preheat Oven: Start by preheating your oven to 350°F (175°C).
2. Brown the Beef: In a skillet over medium heat, cook the ground beef and chopped onion until the meat is browned. Drain excess fat.
3. Mix Ingredients: In a large mixing bowl, combine the cooked beef and onion with the cream of mushroom soup, sour cream, milk, garlic powder, salt, and black pepper. Mix until well combined.
4. Layer Hash Browns: In a greased 9×13-inch baking dish, spread an even layer of the frozen hash brown potatoes at the bottom.
5. Add Meat Mixture: Pour the beef mixture over the hash brown layer, spreading it evenly.
6. Top with Cheese: Sprinkle the shredded cheese generously over the meat mixture.
7. Bake: Place the casserole in the preheated oven and bake for 45-50 minutes, or until bubbly and golden on top.
8. Let it Cool: Remove from the oven and let the casserole cool for 5-10 minutes before serving.
9. Optional Toppings: If desired, sprinkle chopped green onions or more cheese on top for added flavor before serving.

By following these simple steps, you will create a delicious Hamburger Potato Casserole that will leave everyone asking for seconds!