Preheat oven to 450 degrees
Whisk together all the dry ingredients
Cut the butter into small cubes and add to the dry ingredients
Cut the ingredients a bit more by crossing two butter knives (or use a pastry cutter if you have one
Pour in the cold buttermilk and stir with a spoon until a shaggy dough forms
Scoop out onto a floured surface and work the dough lightly until it's incorporated. Try not to let your hands melt the cubes of butter and don't press to hard or overwork the dough.
Form a rectangle about 3/4" thick, then fold. Press down to 3/4" again, then rotate and fold. Do this a couple more times. The folding creates the layers, but keep in mind that you want no more pressure than necessary so that the biscuit will be light and fluffy. Don't use a rolling pin or anything that would overly compress the dough. Just lightly shape with hands.
Cut into squares with a floured knife or rounds with a floured biscuit cutter. Do not slice with the knife or twist the biscuit cutter. Move straight down and up so you don't create a pinch in the side of the biscuit dough that would hinder the rising.
Place them on a sheet pan so they are all touching (this helps with rising). Brush the top with buttermilk and put them in the oven.
Cook 17 minutes