Preheat oven to 475 degrees. Line a baking sheet with parchment paper.
Grate the frozen butter using a cheese grater, and then toss it together with the flour in a medium bowl. Place the butter and flour mixture in the freezer for 10 minutes to chill.
Make a small well in the middle of the flour for the buttermilk, and stir about 15 times to make a sticky dough.
Place the dough on a floured surface, and lightly sprinkle flour over the dough. Using a floured rolling pin, roll the dough out until it's about 3/4 inch thick. Then, fold the dough in half and roll again. Continue folding and rolling the dough 5-6 times (this helps the biscuits get lots of flaky layers).
Next, roll the dough to about a 1/2 inch thickness, and cut with a 2.5 inch floured round cutter (or simply cut into squares if that's easier).
Place the rounds on your lined baking sheet and bake at 475 degrees for approximately 15 minutes (or until lightly browned). Brush with melted butter. Enjoy!
Original recipe from: Southern Living