Preheat the oven to 375°F. In a bowl, sift together the unbleached flour, whole wheat flour, sugar, baking powder, and salt. Stir in the orange zest. Using two knives, cut the butter into the flour mixture until it resembles coarse crumbs.
In a separate bowl, whisk together the egg, buttermilk or sour milk, and vanilla extract. Pour the liquid over the flour mixture all at once and stir just to combine. Stir in the chocolate chips and walnuts.
Line a cookie sheet with parchment paper or grease lightly. Drop the scone batter by heaping spoonfuls onto the cookie sheet, leaving as much space as possible to allow for spreading. Bake for 40 minutes on the center rack of the oven. The scones are done when a cake tester inserted into the center of each comes out clean.