Preheat the oven to 400°F (204°C) and lightly grease a 9x13-inch ceramic or glass baking dish.
In a large mixing bowl, combine the cubed potatoes with melted butter, ranch seasoning, garlic powder, and black pepper.
Toss the potatoes vigorously until the seasoning is evenly distributed and the starch creates a light paste with the butter for extra crispiness.
Transfer the potatoes to the prepared baking dish, spreading them into a single, even layer to ensure uniform roasting.
Roast in the center of the oven for 45 to 50 minutes, using a spatula to flip the potatoes halfway through the duration until they are golden brown and tender.
Remove the dish from the oven and distribute the shredded cheddar cheese and crumbled bacon evenly over the surface.
Return the dish to the oven for an additional 5 minutes, or until the cheese has reached a bubbling, molten state.
Garnish with fresh green onions and serve immediately as a stand-alone comfort dish or a hearty side.