Peel and chop your potatoes into halves or quarters, depending on your preferred size.
Bring a pot of salted water to a boil. Add the potatoes and cook for about 10 minutes, or until they are just tender but not fully cooked.
Strain the boiled potatoes and give them a good shake in the strainer (or toss them in a separate pot). This will rough up the edges, which helps them get crispy during roasting.
Preheat your oven to 392°F (200°C). Add duck fat (or your chosen high smoke point oil) to a baking dish, making sure to cover the entire bottom of the dish. Place the tray in the preheated oven for about 15 minutes, allowing the oil to get hot.
Carefully remove the hot tray from the oven and place your potatoes in it, ensuring each potato is evenly coated with the oil. Be cautious as the tray and oil will be very hot.
Roast the potatoes in the oven for a total of 60 minutes. However, set a timer for 20 minutes to flip the potatoes, ensuring they brown evenly. After turning, roast for another 20 minutes.
While the potatoes are roasting, combine the minced garlic, salt, chopped rosemary, and a drizzle of olive oil in a bowl.
After the second 20-minute timer goes off (40 minutes of total roasting), remove the tray from the oven. Add the garlic mixture and toss the potatoes to evenly coat them. Place them back in the oven and roast for an additional 10-15 minutes, or until the potatoes are golden and crispy.
Remove the tray from the oven. Strain the potatoes to remove any excess oil, then sprinkle with flaky sea salt and chopped fresh parsley. Serve immediately and enjoy!