In a large bowl, combine the 2 cups all purpose flour, white whole wheat flour, baking powder, baking soda, and salt. Scatter the butter pieces over the top, then cut in the butter using your fingers or a pastry cutter
until the mixture resembles a coarse meal. The butter does not need to be uniform—some of the pieces may be the size of pebbles while others can be as large as your thumbnail. Pour 1 1/2 cups, plus 2 tablespoons of the buttermilk over the top and gently mix with a rubber spatula until the mixture just begins to come together. If the dough seems overly dry, add 1 additional tablespoon of buttermilk. It should be moist, but not sticky.