Place the butter in the freezer for 20 minutes to harden.

Meanwhile, whisk together the flour, baking powder, and salt in a large mixing bowl.

Once the butter is hard, grate it using a grater or a food processor. Add the grated butter to the flour mixture and toss gently with your hands to combine, gently breaking up any clumps of butter with your fingers.

Pour in the buttermilk and stir until a soft dough forms. It should be somewhat shaggy.

Dump the dough out onto a lightly floured surface. Gently pat into a rectangle that is about 2 inches high. Fold the dough in half, and use a rolling pin to gently roll the dough into another 2-inch high rectangle. Repeat two or three more times, and roll the final rectangle until it is approximately 1-inch high. You should end up with a rectangle that is approximately 8 inches wide by 6 inches long (it doesn’t need to be perfect).

Cut the dough into 12 square biscuits with a sharp knife. Place the biscuits on a sheet pan and place it in the refrigerator for 30 minutes.

Meanwhile, preheat the oven to 425°F. Bake the chilled biscuits for 10–14 minutes, or until lightly golden brown on the bottom. Serve warm with butter.