reheat the oven to 500°F. In a bowl, combine the flour, baking powder, and salt. Using a pastry cutter or two knives, cut the butter into the flour mixture until it resembles coarse meal. Pour in the buttermilk, and gently mix until just combined.
Turn the dough out onto a lightly floured surface. Knead lightly, using the heel of your hand to compress and push the dough away from you, then fold it back over itself. Give the dough a small turn and repeat 8 or so times. (It’s not yeast bread; you want to just barely activate the gluten, not overwork it.) Using a lightly floured rolling pin, roll the dough out 1/2 inch thick. Cut out rounds of dough with a 21/4-inch round cutter dipped in flour; press the cutter straight down without twisting so the biscuits will rise evenly when baked.
Place the biscuits on an ungreased baking sheet or in an 8- by 2-inch round cake pan. If the biscuits are baked close together the sides will be moist. If the biscuits are baked further apart, the sides will be crisp.
Bake until golden brown, 8 to 10 minutes. Transfer to a rack to cool just slightly. Serve warm.