Preheat oven to 450°F.
In large bowl, sift together the bread flour, baking powder, and salt. Add the whole wheat flour; mix well. Cut in butter until mixture resembles coarse meal or crumbs. Make a hollow in the flour-butter mixture. Stir in enough milk to form a soft dough that gathers together and sticks to the mixing tool. Turn onto a lightly floured surface; knead with the heel of your hand 15 times. Roll 1/4 to 1/2 inch thick; cut biscuit shapes using a 2-inch circle cutter.With a broad spatula, lift cutouts to ungreased baking sheet. Place close together for soft sides, 1-inch apart for crusty sides.
Bake for 10 to 12 minutes or until golden brown. Serve at once.