Preheat the oven to 400 F and line a baking sheet with parchment paper.
Sift together the flour, baking powder, and salt into a large bowl.
Mix the milk and vinegar together and set aside for at least five minutes. This sour milk makes the scones soft and moist.
Grate the butter using a box grater into the dry ingredients. Combine with the flour either using your fingers, a fork, or a pastry cutter. The butter should now be in about pea-sized bits.
Add the goat cheese and chives and mix.
Add the sour cream and the sour milk and mix everything together until it forms a shaggy dough.
Pat the dough out on a clean surface until it is about 1 inch thick.
Cut the dough using a 2-inch circular cutter and place them onto the prepared baking sheet.
Brush the tops of the scones with the beaten egg.
Bake the scones for 20 to 25 minutes, or until the tops are golden brown.