Instructions:
- Preheat oven to 425°F (220°C). Line a large baking sheet with parchment paper.
- Place potatoes in a large stockpot. Cover with cold water, ensuring water level is about 1 inch above the potatoes. Add the 2 Tbsp of coarse salt.
- Bring water to a rolling boil, then reduce heat and simmer until potatoes are easily pierced with a fork but still hold their shape (approx. 20–25 minutes).
- Carefully drain the potatoes thoroughly. Let them sit in the empty pot for 5 minutes to allow excess steam to escape and dry the skins slightly.
- Gently warm the olive oil, smashed garlic, and rosemary sprigs in a small saucepan over very low heat for about 5 minutes. Do not let the garlic brown. Remove from heat and let steep.
- Place the warm, dry potatoes onto the prepared baking sheet, spaced well apart. Using the bottom of a sturdy glass or a potato masher, gently press down on each potato until it is flattened to about 1/2 inch thickness.
- Remove garlic and rosemary from the oil. Drizzle the infused oil evenly over all the smashed potatoes. Season generously with black pepper and the flaky sea salt.
- Roast for 25–35 minutes, flipping halfway through, until deeply golden brown and crisp around the edges.
- Remove from the oven. Sprinkle with a final pinch of flaky sea salt immediately before serving hot.