Whole Wheat Banana Bread

My son, who doesn't usually like bread, loves this recipe!
1 1/2 c whole wheat
1 t baking soda
1 t baking powder
1 t gr cinnamon
4 med ripe bananas, mashed
1/2 c sugar
1 large egg, lightly beaten
2 T oil (preferrable olive oil)
2 t vanilla
1/2 c chopped walnuts
cooking spray

Stir together first 4 ingredients in a large mixing bowl; make a well in center. Stir together bananas and next 4 ingredients; add to flour mixture, stirring just until moistened. Gently fold in walnuts. Pour batter into a loaf pan coated with cooking spray. Bake at 350 degrees for 55 min to an hour. Cool in pan for 10 mininutes and then cool on wire rack. Serve with whipped cream, if desired.