Use the large holes of a box grater to grate the cold butter into a large bowl.
Add the flour, sugar, baking powder, and salt to the butter. Mix with your fingertips to combine. You should still be able to feel pieces of butter in the mixture.
Add the buttermilk and mix gently with your hands to form a dough. Do not knead the dough.
Transfer dough to a generously floured counter. Press down to form a sort of rectangle. Fold in half. Press the dough down to form a rectangle again. Fold in half again then press down and fold one more time. Flour the counter as needed if the dough sticks.
Press the dough so that it is about ¾ inch thick. Cut into about 2-inch rounds using a biscuit cutter or the rim of a glass.
Place the dough rounds on a parchment- or silicone mat-lined sheet pan, making sure the biscuits are touching each other.
Transfer to the oven and bake until golden brown, 13 minutes.
Serve warm with butter slathered on top. These biscuits are also good with jam or served as a side dish with a savory main.
