In a large bowl, whisk together the almond meal, flour, sugar, baking soda, baking powder and salt. Use a fork to toss in the grated frozen butter.
In a separate bowl, whisk together the egg, buttermilk, almond extract and orange zest. Add to the dry ingredients and use a fork to gently combine. As soon as it comes together as a shaggy dough, turn it out onto a lightly floured surface. Gently knead a few times until the dough comes together in a ball. Transfer to a parchment-lined rimless baking sheet.
Flatten the dough into a circle about 9 inches in diameter and cut into 8 triangles, leaving the circle intact. Sprinkle with the sliced almonds and bake 30 minutes, or until golden brown and the centre resists when gently pressed.
Notes
Keep the butter cold: Grating frozen butter and tossing it with a fork keeps it in flakes for tender, flaky scones.Don't overmix: Stop as soon as the dough is shaggy and just holds together — overworking makes scones tough.Two ways to bake: Bake as one 9-inch round cut into wedges (30 min at 375°F), or separate the wedges 2 inches apart and bake at 400°F for 15–20 minutes.Serving: Lovely with jam and whipped cream or crème fraîche.