Preheat oven to 425°F.
Lightly coat the butter in flour. Grate frozen butter using the large holes of a box grater. Work quickly since the frozen butter will begin to soften as you grate. Refreeze if it gets too soft. A food processor with a medium shredding disk works too.
Place grated butter back into the freezer until ready for use.
In a large bowl, combine flour, baking powder, baking soda, salt, and sugar.
Add the butter to the flour mixture and toss to coat.
Create a well in the center of the mixture by pushing the mixture toward the sides of the bowl. Pour buttermilk into the well. Mix gently with a fork just until everything is combined. The dough will be crumbly and shaggy, so avoid over-mixing.
Place the dough on a floured surface and form it into a square about 6 to 7 inches on each side, then roll it into a rectangle about 9 by 12 inches.
First Turn: Position the rectangle so the short side faces you, then fold the dough into thirds by folding the bottom third up and then the top third down like an envelope.
Second Turn: Rotate the dough 90 degrees, then gently roll the dough into a rectangle again. Position the rectangle so the short side faces you, and fold the dough into thirds again.
Third Turn: Rotate the dough 90 degrees, then gently roll the dough into a rectangle again. Position the rectangle so the short side faces you, and fold the dough into thirds again.
Form the dough into an 8- to 9-inch square, place it on a parchment-lined baking sheet, and place it in the freezer for about 10 minutes or until it is firm.
With a sharp knife, trim the edges of the dough, then cut out 9 square-shaped biscuits. Do not twist or pull the knife.
Transfer the biscuits to a baking sheet lined with parchment paper. Place them 1 inch apart from each other and from the edge of the pan. Brush the tops of the biscuits with buttermilk (or melted butter).
Bake for 15-20 minutes or until the tops are golden brown. Rotate halfway through baking.
Let them rest for about 10 minutes, then serve with cream gravy, jam, or make into your favorite biscuit sandwich.