01 - 
                Turn on your oven to 325°F. Coat an 8x5 loaf pan with a generous layer of cooking spray, then add a sheet of parchment paper to the bottom.
              
              
              
                02 - 
                In a medium bowl, stir together cinnamon, flour, baking soda, and salt until they’re evenly blended.
              
              
              
                03 - 
                In a separate bowl, whisk together the egg, sugar, and oil until they form a smooth mixture.
              
              
              
                04 - 
                Gently mix the dry ingredients into the wet mixture. Stir in the buttermilk, mashed bananas, and vanilla until combined.
              
              
              
                05 - 
                Pour the batter into the loaf pan, sprinkle walnuts on top, and bake it for 60-75 minutes. It’s ready when a knife inserted in the center comes out clean.