Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper for easy cleanup if desired.
Wash and peel the potatoes. Cut them into evenly-sized wedges or cubes, about 1 inch thick, to ensure even cooking.
Peel the onion and slice it into thin rings.
In a mixing bowl, combine the potato wedges, olive oil, garlic powder, paprika, salt, and ground black pepper. Toss until the potatoes are well coated with the oil and seasoning.
Spread the seasoned potatoes evenly across the prepared baking sheet in a single layer.
Bake in the preheated oven for 25 minutes.
Remove the baking sheet and add the sliced onions on top of the potatoes.
Return to the oven and bake for an additional 15-20 minutes or until the potatoes are golden brown and crispy, and the onions are tender and lightly caramelized.
Once cooked, remove from the oven and let cool for a few minutes. Garnish with fresh parsley if desired before serving.