1Grate frozen butter on large holes of box grater.
2Add flour, salt, sugar, baking powder, and baking soda to a bowl and whisk together.
3Add frozen grated butter and crumble butter flakes into the flour to create a gravely texture. Work quickly to keep from melting the butter.
4Drizzle in buttermilk while stirring the mixture.
5Flip the dough mix out onto a well floured work surface. Press the powdery mess of dough into a rough rectangle.
6Use a rolling pin to roll dough out into an 18”/45cm long rectangle. Fold the dough - fold top third down over the middle third, then fold bottom (unfolded dough) up over the now folded 2 layers.
7Rotate entire folded mass 90 degrees and use rolling pin to roll out into an 18”/45cm long rectangle again. Fold again as you did the first time.
8Rotate 90 degrees again and flip to the back side. Use rolling pin to roll into an 18”/45cm long rectangle a third time. Fold again.
9Rotate 90 degrees, roll, rotate 90 and roll. In total, you’re rolling and folding 5 times.
10After the fifth fold, flip dough so the bottom side is facing up again and use the rolling pin to pound and flatten the dough just a bit. Place on a tray, cover with a towel, and refrigerate for about 10 minutes to firm up the butter and relax gluten.
11Place now cooled dough onto a floured worksurface and slowly roll out into a 10”x10” (25cm) square.
12Use a floured knife or bench scraper to cut dough into 9 even squares. Transfer squares to a parchment lined sheet tray. Preheat oven and freeze the cut biscuit dough for 20 minutes.
13After removing from freezer, brush tops of biscuit with melted butter then bake at 400F/205C for 20-24 minutes, rotating the tray halfway through baking.