Combine flour, baking powder, sugar, baking soda and salt in large bowl.
Cut in shortening with pastry blender until mixture resembles fine crumbs.
Stir buttermilk into flour mixture until mixture forms a soft dough that leaves sides of bowl.
Turn dough out onto well-floured surface.
Knead dough 10 times.
Roll dough out into 8-inch square.
Cut dough into 16 (2-inch) squares.
Line baking sheet with plastic wrap.
Place squares on lined sheet.
Freeze about 3 hours or until firm.
Remove frozen squares from sheet and place in freezer container.
Freeze up to 1 month.
Preheat oven to 400°F.
Place frozen squares, 1 1/2 inches apart, on ungreased baking sheets.
Bake 20 to 25 minutes until golden brown.