In a large mixing bowl, whisk together the flour, ½ cup sugar, salt, baking powder, and cinnamon
Work in the butter just until the mixture is crumbly. Stir in the apple.
In a separate mixing bowl, whisk together the eggs and applesauce.
Add the liquid ingredients to the dry ingredients and stir until all is moistened and holds together.
Line a baking sheet with parchment and sprinkle it with oat flour.
Scrape the dough onto the floured parchment or pan, divide it in half, then gently pat and round each half into a 5" to 5 ½" circle about ¾" thick.
Stir together 1 teaspoon sugar sugar and ½ teaspoon cinnamon. Brush each circle with a little water or milk, and sprinkle with the topping.
Using a knife knife that you've run under cold water, slice each circle into 6 wedges.
Carefully pull the wedges away from the center to separate them just a bit; there should be about ½" space between them, at their outer edges.
Place the pan of scones in the freezer for at least 30 minutes, uncovered. Then, preheat the oven to 425°F.
Bake the scones for 20-25 minutes, until they're set and golden brown with no wet edges.
Remove the scones from the oven, and cool on the pan for at least 10 minutes.
Notes
Start with cold butter - Use butter straight from the fridge to make your scones, or even better, keep a few sticks of butter in the freezer so they'll be ready the next time you want to make scones.
Freeze the dough - Important! Don't skip this step. The rest in the freezer helps the butter to solidify, which means that when it bakes it will create little air pockets. These in turn create gorgeously flaky layers in the scones. Chilling the dough also keeps the scones from spreading out too much.
Make ahead: You can prepare the scones, place them on a baking sheet, and store them, tightly covered, in the fridge or freezer for up to 24 hours.
Don't overwork the dough - While we're using gluten free flour to make these scones so there isn't any danger of over-activating the gluten in the flour through kneading, it's still a good idea to go light on your handling of the dough. This will lead to more tender scones.
Oat flour substitute - If you can't eat oats, do an equal substitute of sorghum flour or brown rice flour.
Almond flour substitute - Substitute another nut flour of choice, or try teff flour for the almond flour.
Or, use gluten free all-purpose flour - Keep it even easier and substitute 2 ¾ cups of gluten free all purpose flour for the combination of the oat and almond flours.