Add mashed banana, oil, eggs, into a food processor.
Process until well blended. Add dry ingredients and process until uniform batter is formed.
Mix in chopped walnuts.
Pour batter into a greased 9×5 inch loaf pan.
Bake at 325F and start checking for doneness after a half hour. Remove from oven when top is browned and toothpick inserted comes out dry. This could take anywhere from a half hour to 70 minutes depending on pan size and oven.