📋 Instructions

1. 1Preheat and Prep — Preheat the oven to 400F (200C) and line a baking sheet with parchment paper. Whisk the flour, sugar, baking powder, baking soda, cinnamon, nutmeg, and salt in a large chilled bowl.
2. 2Grate the Frozen Butter — Grate the frozen butter on the large holes of a box grater directly into the flour mixture, tossing gently as you go so the shreds stay separate and coated.
3. 3Rub in the Butter — Use your fingertips to work the butter into the flour until it resembles coarse crumbs with a few pea-sized pieces remaining, about 1 minute. Stop there; visible butter bits mean flaky layers.
4. 4Toss the Apples — In a small bowl, toss the diced apple with the 2 tablespoons of flour and a pinch of cinnamon. This coats the fruit so it doesn't release juice and weigh down the dough.
5. 5Mix the Wet Ingredients — Whisk the cold buttermilk, egg, and vanilla in a measuring cup, then pour over the flour mixture. Add the apples and stir with a fork just until a shaggy dough forms, about 15 strokes.
6. 6Shape the Dough — Turn the dough onto a floured surface and pat into a 7-inch round about 1 inch thick. Cut into 8 wedges with a sharp knife, pressing straight down without sawing.
7. 7Chill and Brush — Transfer the wedges to the baking sheet, spacing them 2 inches apart, and freeze for 10 minutes. Brush the tops with buttermilk and sprinkle generously with turbinado sugar.
8. 8Bake Until Golden — Bake at 400F (200C) for 18 to 22 minutes, until the tops are deep golden brown and the centers read 200F (93C) on an instant-read thermometer. Cool on the sheet for 5 minutes before serving warm.