Preheat oven to 425° F. Line a baking sheet with parchment paper.Whisk flour, baking powder, salt, and baking soda together in a large bowl until dry ingredients are well distributed.
Cut butter into flour mixture with a pastry blender or two knives until the mixture resembles coarse crumbs. Add buttermilk; stir until the dry ingredients are just moistened.
Turn dough onto a floured work surface, gather dough together with your hands into a rough rectangle. Fold the rectangle in thirds like a business letter. Turn 90°, gather any crumbs, and pat down into a rectangle. Fold twice more and pat down in between. This helps form the flaky layers.
Roll dough on a floured surface to about 5/8 inch thick. Cut biscuits into 3-inch rounds, Try to cut them close together, because any biscuits you make from the gathered dough scraps won’t rise as high.
Transfer biscuits to the parchment lined baking sheet. Make a slight indent in the top of each biscuit with your thumb. Brush the tops of biscuits with the additional buttermilk. Bake in the preheated oven until golden brown, about 12-15 minutes.
