Preheat the oven to 425˚F (218°C)
Pour the oil onto a sheet pan and place the pan in the preheated oven.
Add two teaspoons of kosher salt to a large pot of water and bring it to a boil.
Add the potatoes and continue to cook over high heat, uncovered, for 5 minutes. Drain in a sieve, then spread the potatoes out on a clean kitchen towel to dry for 5 minutes.
Remove the hot sheet pan from the oven and add the potatoes (the potatoes will sizzle a bit in the hot oil), salt and pepper. Toss them with a metal spatula to coat with the oil and seasoning.
Roast for 35-40 minutes or until golden brown, turning and redistributing them every 10 minutes.
Remove from the oven and add the rosemary and garlic. Toss the potatoes with a metal spatula one more time to evenly distribute the flavorings.
Taste and season with more kosher salt (or flaky sea salt) and pepper, if needed.
Transfer to a serving platter and pray that you made enough.