Place oven rack in upper-middle position and heat oven to 425 degrees. Grease a 9-inch cake pan.
In a large bowl, whisk together all-purpose flour, cake flour, baking powder, baking soda, and salt.
Scatter pieces of butter and shortening across top of flour mixture and use your fingers to rub the butter and shortening into the flour until it resembles coarse meal.
Stir in buttermilk until combined.
Spray a 1/2-cup measuring cup with cooking spray and scoop and drop 6 heaping mounds of dough into prepared cake pan. Place one in the center and the remaining in a circle surrounding the center one.
Bake until golden brown on top, about 20 to 25 minutes. Cool in pan 10 minutes before serving.
Notes
You can use 3 cups of White Lily or Martha White flour instead of a mixture of all-purpose and cake flour.Biscuits are best eaten right away but can be stored in an airtight container at room temperature for 2 days and reheated in a 325 degree oven.Recipe Source: Cook's Country Magazine