Prepare the Pancake Batter: Mash half of the banana in a large bowl. Stir in buttermilk, eggs, and sugar until well combined.
In a separate bowl, whisk together quick-cooking oatmeal, flour, and baking powder. Gradually add this dry mixture to the banana mixture, stirring until just combined—do not overmix.
Cook the Pancakes: Heat a bit of butter in a nonstick skillet over medium heat. Pour ¼ cup of batter per pancake into the skillet. Cook for 2–3 minutes until bubbles form and edges are set. Flip and cook 2–3 minutes more until golden brown. Repeat with remaining batter.
Assemble and Serve: Stack the pancakes and top with sliced banana, chopped walnuts (if using), and maple syrup. Serve with mixed fresh fruit and a glass of cold almond milk. Enjoy!