01 - Place the grated raw potatoes in a clean tea towel and squeeze out as much liquid as possible. Discard the extracted liquid.
02 - In a large bowl, combine the grated raw potatoes, mashed cooked potato, scallions, and optional grated onion until evenly distributed.
03 - In a separate bowl, whisk together the flour, baking powder, salt, and pepper until thoroughly combined.
04 - Add the dry ingredients to the potato mixture and mix well until evenly distributed throughout.
05 - Beat together the milk and egg, then pour over the potato mixture. Stir until just combined; do not overmix to maintain texture.
06 - Heat 1 tbsp each of butter and oil in a large nonstick skillet over medium heat until melted and shimmering.
07 - Drop 2–3 heaping tablespoons of batter per pancake into the pan, flattening each to about ½ inch thick. Cook for 3–4 minutes per side, or until golden brown and crisp.
08 - Transfer cooked boxty to a paper towel-lined plate to drain excess fat. Repeat with remaining batter, adding more butter and oil as needed. Serve hot, garnished with extra scallions if desired.