Preparation

• Mix the yeast, water, and 1 tsp. of the sugar in a small bowl. Let stand until foamy, about 5 minutes.
• Whisk the flour, baking powder, baking soda, salt, and the remaining 1/4 cup sugar in a large bowl. Add the vegetable shortening and cut it in with your fingers until the mixture resembles coarse meal. Grate the butter on the large holes of a box grater. Add to the flour mixture and toss until evenly coated. Add the buttermilk and the yeast mixture, and fold until everything is evenly moistened. Knead gently with your hands in the bowl until the dough forms a ball. Cover tightly with plastic wrap and refrigerate for 2-1/2 hours.
• Turn the dough out onto a floured surface and flatten with your hands into a 1-inch-thick rectangle. Flour the top of the dough and roll into a 13-inch by 17-inch rectangle. Fold in the top and bottom thirds the way you’d fold a letter. Rotate the dough 90 degrees and roll into an 11-inch by 15-inch rectangle. Fold in thirds again, rotate, and roll to a 1/2-inch thickness. The dough should be about 12 inches by 14 inches.
• Using a floured 1-inch round cutter, cut the dough into rounds. Press straight down with the cutter, and cut the rounds as close as possible. Lightly coat 2 baking sheets with nonstick cooking spray and place the rounds on each sheet, spacing them 1/2 inch apart. You can put the scraps on the sheet, too.
• Loosely cover the dough rounds with plastic wrap and let rise while the oven heats to 350°F, about 30 minutes.
• Bake until golden-brown and cooked through, 15 to 20 minutes. Serve hot or warm.