Preheat oven to 450°F (232°C). Line a baking sheet with parchment paper.
Mix dry ingredients. In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
Cut in the butter. Use a pastry cutter or your fingers to work the butter into the flour mixture until it resembles coarse crumbs.
Add buttermilk. Pour in the buttermilk and gently stir until just combined. The dough should be shaggy and slightly sticky.
Shape the dough. Turn the dough onto a floured surface and gently pat it into a rectangle about ¾-inch thick. Fold it over itself and pat it out again (this helps create layers). Repeat 3-4 times.
Cut out biscuits. Use a biscuit cutter (or a floured glass) to cut out biscuits. Place them close together on the baking sheet for soft sides or spaced apart for crispier edges.
Brush with buttermilk for a golden top.
Bake for 12-15 minutes or until golden brown. Let cool slightly before serving.