Preheat and Prep: First things first, preheat your oven to 220°C (200°C fan). Place a large, sturdy baking tray in the oven to heat up. This is a vital step for getting an initial sizzle and a crispier base.

Boil the Potatoes: Wash the potatoes well, leaving the skins on. Place them in a large pot and cover with cold, salted water. Bring to a boil and cook for 15-20 minutes, or until they are fork-tender. You should be able to easily pierce them with a knife with little resistance.

Steam-Dry Thoroughly: Drain the potatoes in a colander and let them sit for a good 5-10 minutes. Shaking the colander once or twice helps. This allows the excess surface moisture to evaporate, which is absolutely critical for crisping them up later. The potatoes should look dry and slightly fluffy on the outside. This is a technique often discussed for achieving the best roast potatoes, as explained by food science experts at Serious Eats.

Prepare the Garlic Oil: While the potatoes are drying, pour the 80ml of olive oil into a small bowl. Add the minced garlic, chopped rosemary, sea salt, and black pepper. Give it a good stir to combine.

Smash the Potatoes: Carefully remove the hot tray from the oven. Drizzle half of the garlic and rosemary oil over the tray. Arrange the steam-dried potatoes on the tray, leaving plenty of space between them. Using the base of a glass or a potato masher, gently but firmly press down on each potato until it's about 1.5-2cm thick. What works best for me is a gentle, even pressure to flatten them without them completely falling apart.

Roast to Perfection: Drizzle the remaining garlic oil over the tops of the smashed potatoes. Make sure the garlic and herbs are distributed evenly. Place the tray in the preheated oven.

Roast for 35-40 minutes: Roast the potatoes, turning the tray halfway through, until they are deep golden brown, crisp, and the edges are slightly darkened. They should look irresistible!

Garnish and Serve: Remove the tray from the oven. Let them cool for a minute or two before using a spatula to lift them off the tray. Transfer to a serving platter, sprinkle with fresh parsley and an extra pinch of sea salt flakes, and serve immediately while they're at their crispy best.