Preheat the oven to 350 degrees F and spray an 8'' or 9'' square baking pan with cooking spray.
Sift or whisk together the flours, baking soda and salt in a small bowl until well combined. In another small bowl, combine the granulated sugar, cinnamon and chopped walnuts.
In a mixer fitted with the paddle attachment or with a hand mixer, beat the butter, canola oil and brown sugar until light and fluffy. Add the eggs one at a time, mixing well after each one is added, and then add in the vanilla. Next, add in the dry ingredients and the yogurt alternately, beginning and ending with the dry ingredients. Finally, fold in the blueberries gently.
Spread half the batter into the bottom of the greased pan. Sprinkle with half the cinnamon sugar/walnut mixture. Spread the rest of the batter on top of the nuts and then sprinkle the rest of the cinnamon sugar/walnuts on top. Bake in the preheated oven for 35 to 45 minutes, or until a toothpick comes out clean when inserted in the center.