01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until evenly distributed.
03 - Add the cold, cubed butter to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining.
04 - In a separate bowl, whisk together the cream, egg, and vanilla extract until fully combined.
05 - Pour the wet ingredients into the flour mixture. Stir gently with a spatula or wooden spoon until just barely combined. The dough should still appear shaggy and slightly dry.
06 - Fold in the chocolate chips, mixing just until evenly distributed. Be careful not to overmix as this will result in tough scones.
07 - Turn the dough out onto a lightly floured work surface. Gently pat it into a 1-inch thick circle, handling the dough as little as possible.
08 - Cut the circle into 8 equal wedges using a sharp knife or bench scraper. Transfer the wedges to the prepared baking sheet, spacing them 2 inches apart.
09 - Brush the tops of each scone with a thin layer of additional heavy cream to promote golden browning.
10 - Bake for 16 to 18 minutes, or until the tops are golden brown and a toothpick inserted into the center comes out clean.
11 - Let the scones cool on the baking sheet for 5 minutes before transferring to a wire rack. Serve warm or allow to cool completely to room temperature.