Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large bowl, whisk together flour, baking powder, baking soda, salt, and sugar (if using).
Cut the cold butter into the flour mixture using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
Pour in the buttermilk and stir gently until just combined. Be careful not to overmix; the dough should be slightly sticky.
Turn the dough onto a floured surface and gently pat it out to about 1-inch thickness. Fold the dough over itself several times to create layers, then pat it out again to about 1-inch thickness.
Use a round biscuit cutter to cut out biscuits and place them on the prepared baking sheet, close together for taller biscuits.
Bake in the preheated oven for 12-15 minutes, or until the tops are golden brown and the biscuits have risen nicely.
Remove from the oven and let cool slightly before serving.