Preheat oven to 450 F.
Place dry ingredients in the bowl of a food processor fitted with a chopping blade and pulse a few times to combine. Add chopped butter and pulse until the mixture resembles coarse meal.
Add buttermilk and mix until just combined. The mixture should be very moist.
Dust a work surface with flour and dust your hands with flour. Transfer the mixture to the floured work surface and gently pat until about 1" thick.
Fold the dough in half horizontally, then vertically, repeating so you fold the dough a total of 5 times. Gently pat into a circle about 1" thick and use biscuit cutters (I use 2") to cut the dough. You should be able to get about 8 biscuits, then gently pat the scraps back together and cut two more biscuits. Place close to each other on a baking sheet and brush with melted butter and lightly sprinkle with sugar.
Bake for 10-12 minutes or until the tops are golden. Remove from oven. These can be served at any temperature.