1. Preheat the oven to 350°F (180°C). Lightly grease a 9×5 inches loaf pan and line with a piece of baking parchment. Set aside. Add chia seeds and water to a small bowl and let sit for 3-4 minutes until thickened. Chop the walnuts and set aside.

2. Add the bananas to a bowl and mash. Add the oil, oat milk, maple syrup, and vanilla extract and mix to combine. Next, add the thickened chia seeds and mix in as well. Set aside.

3. In a large bowl mix the flour with baking powder, ground cardamom, and salt. Add the banana mixture and stir in. Add most of the chocolate chips and walnuts (keep some for decorations) and fold in. Transfer the batter to the prepared loaf pan. Cut the additional banana lengthwise in half and add on top of the batter. Sprinkle the rest of the chocolate chips and chopped walnuts on top.

4. Bake the banana bread for 55-60 minutes in the preheated oven. Check with a wooden skewer if the cake is done – if it comes out clean the banana bread is done. Take out of the oven and let cool down for a while in the pan, then lift out with the baking parchment and let cool down completely on a wire rack.