Preheat oven to 450 F. (read the tips in the notes before proceeding)
Add flour into a large bowl.
Grate the frozen butter into the flour.
Using a pastry cutter, cut in the butter until the mixture resembles coarse crumbs.
Pour in the cold buttermilk and stir with a rubber spatula until a dough form.
Lightly flour a work surface, and turn the dough out onto the work surface.
Flour your hands and gently knead the dough, add more flour as needed but not too much. Dough should be slightly sticky.
Fold the dough several times to create layers. Work quickly to prevent the dough from warming, which could result in a flat, dry biscuit.
Finally pat the dough into a 1-inch thick rectangle.
Using a 3-inch biscuit cutter, cut out 4 biscuits. ( Regather the dough and pat it back out to cut the remaining biscuits.)
Place biscuits on a baking sheet, with the sides touching.
Bake for 12-14 minutes. (Optional- During the last minute or two: Brush the tops lightly with extra melted butter and then switch the oven to broil to brown the tops if needed. Keep an eye on it the entire time while broiling since the browning happens quickly.)
As soon as biscuits come out of the oven, brush with melted butter. Once the butter has absorbed, brush them once more.