Heat oven to 425°F. Line a large rimmed baking sheet with foil or parchment.
Cook bacon in a skillet over medium heat until crisp, 8–10 minutes. Drain on paper towels and chop.
Toss potatoes with olive oil, garlic powder, onion powder, paprika, salt, and pepper on the baking sheet.
Roast 25 minutes. Stir and roast 10–15 minutes more, until browned and fork-tender.
Dot potatoes with butter. Sprinkle cheddar and half the bacon evenly over the top.
Return to oven 3–5 minutes to melt the cheese. Broil 1 minute if you want extra color.
Scatter on remaining bacon and the green onions. Dollop with sour cream and serve hot.