In a large mixing bowl, whisk together the gluten-free flour, sugar, baking powder and salt.
Grate the frozen butter using a box grater. Add it to the flour mixture and combine with a pastry cutter, two forks, or your fingers until the mixture comes together in pea-sized crumbs.
Stir in the mix-ins to the flour mixture until evenly distributed. In a separate bowl, whisk together the sour cream, egg and vanilla until combined.
Using a rubber spatula, stir the sour cream mixture into the flour mixture until no dry bits of flour remain. Stir in the mini chocolate chips.
Spread out a large piece of plastic wrap. Using wet hands, transfer the dough to the parchment paper. Clean and wet your hands again then pat the dough to form a 6-inch round that is 1-inch thick. Wrap the dough tightly in plastic and refrigerate for 30 minutes. (Do not refrigerate longer than 30 minutes.)
Preheat the oven to 500F. Line a baking sheet with a silicone mat or parchment paper.
After 30 minutes take the dough out of the fridge. Spray a sharp knife with vegetable oil and cut the dough into 6 equal wedges. Arrange the scones on the prepared baking sheet. Sprinkle with coarse sugar if desired.
Lower the oven temperature to 425F and bake the scones for 12-14 minutes until golden brown. (You want the oven temperature to be hot to start so the scones turn golden brown as they cook through.)
Transfer the scones to a cooling rack and let cool for 20 minutes before serving. Enjoy!