Slice the cold butter into 1/4-inch-thick (6-mm) slices. Dump the flour in a large bowl and toss in the butter slices. Using a pastry blender or a couple knives, cut the butter into the flour until the mixture is pretty crumbly and resembles small peas. Cover and refrigerate for 10 minutes.
Preheat the oven to 450°F (230°C). Lightly butter a baking sheet or line it with parchment paper.
Add the buttermilk to the flour mixture, gently stirring with a fork just until the flour is moistened. The dough will be very sticky. Turn the dough out onto a lightly floured surface and gently knead it 3 or 4 times, gradually adding additional flour as needed. Using floured hands, press or pat the dough into a 3/4-inch-thick (18-mm) rectangle (it should measure about 9-by 5-inches or 23-by 13-cm). Sprinkle the dough with a little additional flour.
Starting at a short end, fold the dough over onto itself in 3 sections as if folding a letter-size piece of paper. You should end up with a rectangle shape. Press the dough into a 3/4-inch-thick (18-mm) rectangle (yes, again) and repeat the entire process 2 more times, adding additional flour as needed.
Press or pat the dough to a 1/2 inch (12-mm) thickness on a lightly floured surface. Cut the dough with a floured 2-inch (5-cm) cutter. Place the biscuits side by side on the prepared baking sheet. The biscuits should touch. Quickly and gently press together the dough scraps while the dough is still cold and cut out as many more biscuits as you can.
Bake the biscuits for 13 to 15 minutes, or until lightly browned. Brush the tops with the melted butter and let them cool ever so slightly. The biscuits are best warm from the oven. Don’t dally.