Direction

1. Whisk together flour, baking powder, sugar, salt, and baking soda in a large bowl. Add shortening; using your fingertips, pinch and work shortening into flour mixture until mixture resembles coarse cornmeal. Grate butter using large holes of a box grater into flour mixture. Toss and pinch quickly with your fingers until all butter pieces are well-coated in flour mixture, about 30 seconds.
2. Lightly spray work surface with cooking spray, and sprinkle with flour. (Spray keeps flour in place.) Add buttermilk to flour mixture in bowl, and stir together to form a shaggy, sticky dough with no dry flour remaining. Turn dough out onto prepared work surface. Lightly coat hands with flour; gently pat dough using heels of hands to form a 1/2-inch-thick rectangle (about 11 x 7 1/2 inches). Fold rectangle into thirds (like folding a letter). Repeat process of patting and folding 2 times.
3. Preheat oven to 450°F. Using a lightly-floured 2 1/4-inch round cutter, cut dough, stacking, reshaping, and cutting scraps until all dough is used. Turn dough rounds smooth side up; arrange 3/4 inch apart on a baking sheet lined with parchment paper. Refrigerate, uncovered, until cold, about 15 minutes.
4. Bake chilled dough in preheated oven until tops are golden brown and lightly crisped, 16 to 20 minutes. Let biscuits cool on pan 5 minutes.