Prep: Preheat the oven to 420°F (220°C). Place a dark-colored baking sheet in the oven to heat up.
Season the potatoes: Carefully toss the potatoes in a large bowl with olive oil, garlic powder, paprika, salt and black pepper. Make sure all potatoes are evenly coated.
Add potatoes to baking sheet: Carefully remove the preheated baking sheet from the oven using oven gloves. Spray with a light coating of oil. Place the potatoes on it in a single layer. Tuck the rosemary sprigs in between the potatoes.
Bake: Bake the potatoes for around 25-30 minutes, or until tender on the inside and browned on the outside. You can finish under the broiler for 2-3 minutes to really brown the top as well.
Garnish: Sprinkle the hot potatoes with black pepper, sea salt flaked and fresh parsley, if you like. Serve immediately.