This is my grandmother's original biscuit recipe from my very first season of Good Eats: light, flaky, and perfectly buttery. Let me just say that the most important recipes you can collect are family recipes. When a couple gets married, the best gift they can receive is a handmade book of recipes from both sides of the family. A note on mixing: This method of rubbing or "cutting" fat into flour, then stirring in moisture before kneading is referred to as the "biscuit" method and is called for in the preparation of many baked goods, most notably scones, shortbread, and pie crusts.This recipe first appeared in Season 1 of Good Eats and was updated in Season 1 of Good Eats: Reloaded.
In a large mixing bowl, combine flour, baking powder, baking soda and salt. Using your fingertips, rub butter and shortening into dry ingredients until mixture looks like crumbs. (The faster the better, you don't want the fats to melt.) Make a well in the center and pour in the chilled buttermilk. Stir just until the dough comes together. The dough will be very sticky.
Turn dough onto floured surface, dust top with flour and gently fold dough over on itself 5 or 6 times. Press into a 1-inch thick round. Cut out biscuits with a 2-inch cutter, being sure to push straight down through the dough. Place biscuits on baking sheet so that they just touch. Reform scrap dough, working it as little as possible and continue cutting. (Biscuits from the second pass will not be quite as light as those from the first, but hey, that's life.)
Bake until biscuits are tall and light gold on top, 15 to 20 minutes. Serve hot.