Creating cheesy potatoes is straightforward if you follow these simple steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Prepare Potatoes: Peel and dice the potatoes into even cubes.
3. Boil Potatoes: Place the diced potatoes in a large pot and cover with water. Bring to a boil and cook until tender, about 15-20 minutes.
4. Drain and Cool: Drain the potatoes and let them cool slightly.
5. Mix Ingredients: In a large mixing bowl, combine the shredded cheddar cheese, sour cream, milk, chopped green onions, garlic powder, salt, and black pepper. Stir until well mixed.
6. Combine with Potatoes: Add the cooked potatoes to the cheese mixture, folding gently to combine without mashing the potatoes.
7. Transfer to Baking Dish: Pour the potato mixture into a greased 9×13-inch baking dish, spreading it out evenly.
8. Add Topping: Sprinkle the shredded mozzarella cheese evenly over the top of the potato mixture.
9. Bake: Place in the preheated oven and bake for 30-35 minutes or until the cheese is bubbly and golden brown.
10. Cool: Remove from the oven and allow it to cool for about 10-15 minutes before serving.

These steps will guide you in creating this incredible cheesy potato dish effortlessly.