I like making biscuits in the food processor, mainly because the chilled butter gets cut into the flour very quickly. Half a cup of butter is a lot, but I have tried making these with less and haven't liked them as much.
1 cup cake flour
1 cup whole wheat pastry flour
2 tsp baking powder
1/2 tsp baking soda
1/4 tsp salt
1/2 cup chilled butter
3/4 cup cold buttermilk
Preheat oven to 400°F.
Place the flours, baking powder, baking soda and salt into the bowl of a food processor. Pulse a few times to combine everything.
Cut up the butter into a few pieces and place on top of the flour. Pulse a few more times until the butter is cut up and the mixture resembles course meal.
Remove the top and pour the buttermilk evenly over the surface. Replace the top and pulse until the dough begins to look chunky.
Sprinkle a bit of flour onto a surface and remove the chunks of dough from the food processor. Knead once or twice; only enough to form a single piece of dough. Shape into a rectangle about 1 1/4 inches high and cut into 8 pieces.
Place the cut biscuits onto cookie sheet lined with parchment paper or a silicone mat. Bake for about 12-15 minutes or until the biscuits are golden brown.