Preparation

• Preheat oven to 400 degrees. Whisk together flour, oats, brown sugar, cinnamon, nutmeg, baking powder, baking soda, and salt. Cut in butter with a pastry blender or rub in with your fingers. (The largest pieces should be the size of small peas.) With your fingertips, flatten butter pieces into small disks. Add apples and buttermilk, stirring until dough just comes together.
  
  Turn out dough onto a lightly floured work surface. Pat dough into a 6-by-8-inch rectangle, and cut into twelve 2-by-2-inch squares with a floured knife. Place about 2 inches apart on parchment-lined baking sheets. Brush tops with buttermilk, and sprinkle with raw turbinado sugar and oats. Bake until golden brown, 20 to 22 minutes, rotating sheets halfway through. Let cool on sheets for 15 minutes. Serve warm or at room temperature.