Preheat the oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, sugar, baking powder and salt.
Grate the cold butter on the large hole of a box grater then add it to the bowl. Using your fingers, work the butter into the flour until the mixture is the consistency of wet sand. (See Kelly’s Note.)
In a separate medium bowl, whisk together the heavy cream, sour cream, eggs and vanilla.
Add the wet ingredients to the dry ingredients and using a spatula, mix just until combined. (Do not overmix the dough.) Stir in the chocolate chips.
Lightly flour your work surface then turn out the dough. Gather it together and shape it into an 8-inch round disk. Using a sharp knife, cut the disk into 8 wedges.
Arrange the scones on the baking sheet then brush the tops of them with heavy cream. Sprinkle the scones with sanding sugar (optional).
Bake the scones for 22 to 25 minutes until they are pale golden. Remove them from the oven and let them cool for 5 minutes on the baking sheet before serving.