Preheat the oven to 350°F (180°C) and grease a 9x5 inch (25x13cm) loaf pan with oil or vegan butter. Then line the pan with a strip of parchment paper.
To a medium-size bowl, add all-purpose flour, baking powder, baking soda, ground cinnamon, and a pinch of sea salt. Mix with a whisk and set aside.
Add bananas to a large bowl and mash them well with a potato masher or fork into applesauce-like consistency. Add maple syrup, peanut butter, sunflower oil, and apple cider vinegar, and stir to combine.
Sift the flour mixture into the mashed banana mixture and mix everything with a spatula until just combined. Don’t overmix the batter. Finally, fold in chocolate chunks.
Pour the batter into the prepared baking pan, spread it evenly, and top with more chocolate chunks. Bake it in preheated oven for 35 minutes. The bread is done when a toothpick inserted in the middle comes out clean. If it looks wet, bake for additional 5-10 minutes.
Remove the bread from the oven and let cool for about 15 minutes. Then carefully remove the bread with the parchment paper flaps on the sides and place it on a cooling rack to let cool completely.