Directions

1. Bring potatoes to a boil in a pot of salted water. Reduce heat, and simmer until fork tender, 10 to 12 minutes. Drain well.
2. While still warm, push potatoes through the large holes of a ricer, or use a potato masher to mash them until smooth (you should have 2 1/2 cups). Stir butter into warm potatoes until combined well. Stir together flour, baking powder, 1 heaping teaspoon Kosher salt (or about 1 tsp table salt), and 1/4 teaspoon pepper, then stir into potatoes with a wooden spoon until just combined. Form dough into a ball on a lightly floured work surface. Cover and let cool for a few minutes.
3. Dust work surface with flour, and pat dough into an 8-by-10-inch rectangle. Sprinkle half with cheese and green onions, and fold to create a 4-by-10-inch rectangle. Press down so top and bottom pieces of dough come together. With a floured knife or bench scraper, cut dough into four 2 1/2-by-4-inch rectangles, then cut each in half diagonally.
4. Heat a griddle, large cast-iron skillet, or non-stick skillet over medium heat, and add 1 teaspoon butter. When it has completely melted and is sizzling, cook 4 scones until golden brown and cheese melts, 3 to 4 minutes per side. Keep scones warm in a 200-degree oven while you cook the remaining dough.
5. Serve warm.