Whisk the flour, sugar, salt, and baking powder together in a large mixing bowl. Grate butter and mix in the bowl with the rest of the mixture. Pour in the chocolate chips and mix again.
In a different mixing bowl, pour in sourdough starter, heavy cream, eggs, milk, and vanilla extract. Whisk together.
Pour the second mixture into the large mixture with the first mixture. Mix with your hands until it makes a dough.
Put the dough on a clean surface and flatten it into a circle shape about an inch thick. Then cut into pieces. You can make 8 scones if you want large scones or 16 if you want smaller scones.
Line a baking sheet with parchment paper. Place the scones on the baking sheet. Mix the heavy cream and sugar and brush on the scones.
Put the baking sheet with the scones into the freezer and preheat the oven to 425 degrees.
Once the oven is preheated, bake the scones in the oven for 14-17 minutes until they are golden brown.
Mix the powdered sugar, vanilla, and milk for the glaze in a small bowl. Drizzle over the scones.
Wait until they cool and serve.