The cowboys like to call these hot rocks, but that's just because they're used to eating them hard old things Cookie bakes out on the trail. I'm sure rocks would never melt in yer mouth the way my buttermilk biscuits do.
In a large mixing bowl, combine the flour, baking powder, baking soda and salt. Cut the butter and shortening into dry ingredients until mixture looks like crumbs. You can use a pastry cutter or two knives to cut it in, but I like to use my fingers and do it fast so the fats don't melt. Make a well in the center of your flour mixture and pour in the buttermilk. Stir just until the dough comes together. The dough will be very sticky, but that's ok.
Turn the dough out onto a floured surface, dust the top with flour and gently fold dough over on itself 5 or 6 times. Press it into a 1-inch thick round, then cut out biscuits. I use my favorite 2-inch cutter and make sure I push straight down through the dough. (It makes your biscuits rise up real tall.
Place yer biscuits on a baking sheet so that they just touch. Reform the scrap dough, working it as little as possible and keep cutting till you use up all the dough. (The first biscuits you cut will be lighter and taller than the rest, but I never had a cowboy complain about the others.)
Bake yer biscuits until they're tall and light gold on top - about 15 to 20 minutes should do it.
Serve them up nice and hot with butter, honey, jam or apple butter on the side.
Preheat the oven to 450.