Cut the butter into cubes and put in the freezer while you prepare the rest of the ingredients.
In a large mixing bowl, combine the dry ingredients: flour, sugar, baking powder, chocolate chips, and salt. Stir to mix.
In a separate bowl, whisk together the wet ingredients: egg, sourdough starter, heavy cream, and vanilla extract.
Using a pastry blender, cut the cold butter into the dry ingredients until the mixture resembles small peas.
Pour the liquid ingredients into the large bowl with the dry mixture. Mix initially with a spoon, then use your hands to knead the dough just until it forms a ball. Avoid over-kneading the dough; less handling is better. It should be shaggy & rough.
Transfer the dough to a lightly floured surface, shaping it into a disk that's about one inch (2.5cm) thick. Divide this disk into eight wedges using a sharp knife.
Preheat your oven to 400 degrees F (200C). While the oven heats, chill the unbaked scones in the refrigerator for 10 to 15 minutes. Prepare a baking sheet by lining it with parchment paper.
Once the oven is at temperature, take the dough out of the fridge, arrange the scones on the prepared baking sheet ensuring they do not touch. Use a bench scraper to help with the transfer.
Bake for 20-25 minutes or until they are golden brown. After baking, transfer the scones to a wire rack to cool.