• Preheat oven to 425°F. Line a baking sheet with parchment paper and set aside.
• In a medium bowl, stir together flour, baking powder, baking soda, salt, sugar, cinnamon, and orange zest. With a rigid pastry blender or two knives, cut in butter until mixture resembles coarse meal. Make a well in the center, and then add buttermilk and egg. Stir just until combined, taking care to not overmix. Gently fold in chocolate. The dough will have a shaggy appearance.
• Handle the dough as little as possible to keep the butter and chocolate cold - this will give you flakier scones. Quickly gather up the dough in the bowl with your hands, somewhat squeezing it to bind it altogether into a single round of dough. Place dough on a lightly floured work surface and knead 5 to 6 times, which will make everything come together into a smoother dough. Quick shape dough into a ball, place it on your lightly floured surface, and pat into an 8″ diameter disk. Then cut the disk into 8 wedges, using a stiff bench scraper or large non-serrated knife. When cutting, press straight down with the bench scraper, then pull it straight back up; do not saw or cut back and forth horizontally, as this will hinder the rise and overall flaky texture.
• Transfer wedges to prepared baking sheet, leaving at least 1" of space between each scone. Bake until scones are golden brown, 12 to 15 minutes. Remove from oven and let scones sit on baking sheet for a couple minutes before removing to a wire rack.

Orange Glaze

• While scones are still warm, prepare the glaze. In a small bowl, whisk together all glaze ingredients until smooth. Adjust thickness as needed (add more powdered sugar if too thin or more orange juice if too thick), until you have a thickened glaze that drizzles slowly into ribbons. Once the scones are only just slightly warm, drizzle the orange glaze over the scones in a zig-zag pattern.
• Serve while still warm or at room temperature. Best eaten on the day they are baked.