In a large bowl, whisk together the cake flour, sugar, baking powder, baking soda, and salt. Set aside.
In a liquid measuring cup, whisk together the sour cream, heavy cream, and vanilla extract until well combined.
Grate the frozen butter using the large holes of a box grater. Alternatively, you can slice the butter into small cubes with a knife for more defined, flaky layers.
Toss the butter into the dry ingredients until evenly coated, then use your fingers to flatten the butter into pea-sized pieces. Add in the chocolate chips.
Pour in the wet ingredients and stir until the flour is hydrated. Once a dry, shaggy dough begins to form, turn it onto a work surface and pat it into a rectangle that's roughly 1'' thick.
Using a bench scraper or knife, slice the dough into two even squares. Stack each piece on top of one another, sandwiching any dry bits of dough in between the layers, then press down to flatten. Repeat this process of lamination two more times. If at any point the butter becomes too warm, wrap the dough in plastic and refrigerate for 10 to 15 minutes before proceeding with the recipe.
After your last round of lamination, form the dough into a 7.5'' disk roughly 1 to 1.5'' inches tall. With a sharp knife or bench scraper, slice the circle into 8 even wedges.
Evenly space the scones onto a parchment-lined baking sheet and freeze for 10 minutes. In the meantime, preheat the oven to 425℉.
After 10 minutes, remove the scones from the freezer. Brush the tops with heavy cream and sprinkle over demerara or turbinado sugar.
Bake for 5 minutes at 425℉, then reduce the oven temperature to 400℉ and cook for 15-20 minutes more or until the scones are golden brown and cooked through. Do not overbake.
Remove the pan from the oven and allow to cool slightly before serving. Leftovers will keep in an airtight container at room temperature for 1-2 days.