Preheat the oven to 400 degrees. Line a baking sheet with parchment paper and set it aside.
Mix together all the dry ingredients in a medium-sized bowl.
In another smaller bowl, mix together the buttermilk, 1 egg, and vanilla. Set this aside.
Cut chilled butter into ½-inch chunks then add them to the dry mixture.
Break up the butter chunks into small pea-sized pieces, This can be done with your hands or with a pastry cutter.
Add the buttermilk mixture to this and mix until all the dry ingredients are incorporated. Do not overmix.
Add in the chocolate chips. Turn it out onto a lightly floured surface
If you are cutting them into triangles as I did, divide it into 2 equal pieces, Gently press each into 2 8-inch circles. Cut each circle into 8 pieces. Cut it into quarters, then each quarter in half.
Place each of these onto the lined baking sheet. Mix together the egg wash and brush it over the scones, then sprinkle with sugar. Move these to the oven and bake for 17 minutes.
Remove and let them cool slightly before serving.