Preheat and Prepare
Preheat your oven to 375°F (190°C).
Lightly grease a 9x13-inch baking dish or line with parchment paper.
Prepare the Potatoes
Wash and dice the potatoes into bite-sized pieces.
Place the potatoes in a large mixing bowl.
Make the Sauce
In a small bowl, mix the sour cream, melted butter, garlic powder, onion powder, and black pepper.
Pour the sauce over the potatoes and toss to coat evenly.
Assemble the Dish
Spread the coated potatoes evenly in the prepared baking dish.
Sprinkle the shredded cheddar cheese on top.
Bake
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15–20 minutes, or until the potatoes are tender and the cheese is melted and bubbly.
Garnish and Serve
Remove from the oven and let cool for a few minutes.
Sprinkle with sliced green onions if desired. Serve warm.