Preheat oven to 350 F. Spray a 9" x 5" loaf pan with nonstick spray. In a medium bowl, combine dry ingredients. Set aside. In a large bowl, mix together yogurt and sugar. Add egg and combine. Stir in orange juice. Add dry mixture to wet mixture. Mix only until just combined. Carefully fold in orange zest, cranberries, and walnuts. Pour into prepared pan. Bake for 1 hour or until a toothpick inserted comes out clean. Cool in pan on a wire rack for 10 minutes. Carefully invert pan to remove, and finish cooling on rack. Wrap in plastic and foil.