In a large bowl, thoroughly whisk together the flours, sugar, baking powder, baking soda and kosher salt. Cut the vegan butter into small chunks and add to the flour. Use a pastry cutter to cut in the butter until crumbly.
In a glass measuring cup or small bowl, whisk together the oat milk, vanilla and orange zest.
Pour the oat milk mixture into the center of the flour (and any mix ins, if using) and gently stir with a spatula until a crumbly dough just comes together.
Turn the crumbly dough out onto a lightly floured surface and use your hands to gently pat it into a large rectangle. Fold over the rectangle, placing any floury crumbles in the middle of the fold, and continue patting. If the dough is still floury, fold one more time in the same manner. Then pat into a 7” circle about 1 inch thick. The dough should be more incorporated and fairly firm at this point, try not to overwork the dough. Carefully transfer the dough round to a cutting board and chill in freezer for 6 minutes.
Preheat the oven to 425°F. Line a baking sheet with parchment paper.
After chilling, use a large knife to slice the dough into 8 pie shaped pieces. Carefully transfer the scones slices to the tray and space evenly in two rows. Lightly brush the top of the scones with a bit of oat milk, then place the tray into the freezer and freeze additional 12 minutes.
After chilling, add the baking tray directly to the hot oven and bake for about 17 to 20 minutes until golden brown.
Cool on a cooling rack and allow to cool to room temperature. If desired, once cooled make the 1 Minute Powdered Sugar Icing and spread it on top of each scone. (Here we used cranberry juice in place of the milk to make a pink icing, then topped it with crushed pistachios.)
Storage info: Serve immediately; scones are best the day of baking. They keep well at room temperature for 2 days or in the refrigerator for 5 days. You also can freeze them: cool them to room temperature, then place them in a freezer-friendly bag or container. To thaw them, leave them on the counter for a few hours or in the refrigerator overnight. They’re best room temperature, but if you’d like them warmed, place in a 300 degree Fahrenheit oven for about 10 minutes until warmed through.