Prepare the corn bread: Place a rack in the center of your oven and preheat the oven to 425°F. Lightly coat an 8x8-inch dish with cooking spray. In a large mixing bowl, combine the cornmeal, all purpose flour, whole-wheat flour, baking powder, and salt. In a separate bowl or large measuring cup, combine the milk, canola oil, and egg. Make a well in the center of the flour mixture, pour in the liquid ingredients, and then stir just until moist (the batter may be lumpy, but do not over mix). Fold in the cheddar cheese. Spoon the batter into the prepared dish and bake for 16 minutes, or until a wooden pick inserted in center comes out clean. Cool 5 minutes in pan on a wire rack. Remove from pan to cool completely. Reduce oven temperature to 350°F.