1. Preheat the oven to 350°F (180°C). Grease a loaf tin (about 9×4 inches) and line with a stripe of baking parchment. Set aside.

 

2. Add the flour, baking powder, baking soda, and salt to a small bowl and mix. Set aside. Chop the walnuts and set aside. Mash the bananas and set aside as well.

 

3. Add the butter and sugar to a large bowl and mix until light and fluffy. Add the eggs one by one and mix until well after each addition. Add milk, vanilla extract, and mashed banana and mix in. Add the flour mixture and mix until just combined. Add about 2/3 of the chopped walnuts and fold in. Pour the batter into the prepared loaf tin and smooth out the top. Cut the banana for the decoration lengthwise in half and place (with the cut sides up) on top of the dough. Sprinkle with the remaining walnuts and bake for about 55-60 minutes or until a skewer inserted into the center comes out clean. Take out of the oven and let cool down in the baking tin for about 10 minutes, then remove carefully and let cool down completely on a wire rack.