To make these best-ever buttermilk biscuits, preheat the oven to 475 degrees. Sift 2 cups all-purpose flour, 4 teaspoons baking powder, ½ teaspoon baking soda and ½ teaspoon salt into a large bowl. Cut in ¼ cup vegetable shortening with a pastry blender or two knives until the mixture resembles coarse meal. Add 1 cup buttermilk and stir with a fork until just combined. Turn the dough out onto a lightly floured surface. Roll to a thickness of ½ inch. Do not overhandle the dough as this will result in tough biscuits. Cut out the biscuits with a 2-inch round, floured cutter. Place the biscuits, spaced so they don’t touch, on an ungreased baking sheet. Bake about 12 minutes or until their tops are light golden brown.