Before you begin, place sticks of butter in freezer for at least 30 minutes.
Whisk flour, sugar, baking powder, baking soda and salt in a large bowl. Remove sticks of butter from freezer and toss in flour mixture to coat. Grate approximately 7 tablespoons from each stick on large holes of box grater directly into flour mixture.
Toss gently to combine and discard remaining butter.
Add buttermilk to flour mixture and fold with a wooden spoon or spatula, just until combined. Dough will look dry at first.
Transfer dough to floured surface. Dust surface of dough with flour and use floured hands to press dough into a rough 7-inch square.
Roll dough into 12x9-inch rectangle with the short side parallel to counter. Starting with the side closest to you, use a bench scraper or spatula to fold the dough into thirds (like a letter). Press edges of dough to seal.
Turn dough by 90 degrees clockwise. Repeat rolling into rectangle, folding into thirds, and turning clockwise an additional 4 times for a total of 5 sets of folds. After the final set of folds, roll dough into an 8 ½-inch square about 1 inch thick.
Transfer dough to a rimmed baking sheet lined with parchment paper. Cover with plastic wrap and refrigerate for 30 minutes. Place rack in upper-middle position in oven and preheat to 400°F.
Once dough is chilled, transfer to a lightly floured cutting board. Using a sharp, floured knife, trim ¼ inch of dough from each side and discard. Cut remaining dough into 9 equal squares. Arrange biscuits 1 inch apart on baking sheet. Melt 2 tablespoons of butter and brush tops of biscuits.
Bake until biscuits are golden brown, 22-25 minutes, rotating sheet halfway. Transfer biscuits to a wire rack to cool for 15 minutes before serving. Enjoy!