01 - Place the peeled and quartered potatoes in a saucepan with salted water. Bring to a boil and cook until fork-tender, approximately 15 minutes. Drain thoroughly and return to the hot pot to evaporate any residual moisture.
02 - While the potatoes are still warm, mash them meticulously until completely smooth and free of lumps.
03 - Add the specified amount of unsalted butter and whole milk to the mashed potatoes. Mix vigorously until thoroughly combined and smooth.
04 - In a large mixing bowl, whisk together the all-purpose flour, fine sea salt, and baking powder. Gradually incorporate the warm potato mixture into the dry ingredients, mixing gently until a soft, cohesive dough forms.
05 - Transfer the dough to a lightly floured work surface. Briefly knead until the dough is smooth. Pat or roll the dough out to an even thickness of approximately 1/2 inch.
06 - Using a knife or a round cutter, divide the flattened dough into 8 uniform triangles or rounds.
07 - Heat a non-stick skillet or griddle over medium heat. Cook the potato bread slices in batches for 3–4 minutes per side, until they achieve a golden-brown color and a crisp exterior.
08 - Serve the potato bread warm, generously spread with additional unsalted butter.