Preheat the oven to 425°F (218 °C) and grease or line a 12 well or 2 x 6 well muffin pans.
Mash the bananas really well with a fork or potato masher until they are a slightly lumpy puree.
Add the cashew (or other nut/seed) butter, maple syrup, vanilla extract, sugar and salt to the bananas and whisk together until really well combined.
Add the flour, baking powder, baking soda and cocoa powder and fold it in gently BY HAND (not with a mixer, food processor or blender) until everything is just combined. Do not over mix because it will affect the texture and rise of the muffins.
Finally add the chocolate chips and fold them in just enough to distribute evenly.
Spoon the batter evenly into the prepared muffin pan and sprinkle the tops of each with a few more chocolate chips.
Place them in the oven and set a timer for 5 minutes. Once the 5 minutes has passed, immediately turn the oven down to 375°F (190°C) without peeking or opening the door and cook for a further 13 - 14 minutes. Check them with a toothpick and if it comes out mostly clean then they are done. It is important not to over-bake these muffins. If anything they are better very slightly underdone to keep their moist fudginess.
Remove from the pan and place on a wire cooling rack and allow to cool, although I do recommend eating one (very carefully) while still hot...Purely for research purposes of course....
**Bananas – The bananas should be about 8 inches in length and once peeled the total weight of the 3 bananas should be about 375g / 13 oz. A few grams either side is ok though. It doesn’t have to be exact.Cashew butter has the most neutral flavour so is my nut butter of choice but any nut or seed butter will work.Be sure to use good quality nut butter without additives. I always make sure to buy brands with nuts or nuts and salt as the ingredients and have not tested this recipe with the more processed kinds with added sugar and artificial ingredients.Do not skip the maple syrup or replace it with sugar. The maple syrup is what keeps these muffins moist and fudgy.I have not tested this cake with any other flours except spelt or all purpose. If you use another kind you do so at your own risk. I can't recommend spelt flour enough though for muffins or cakes like this. It gives excellent results. Much lighter and fluffier than all purpose flour or wholewheat. Store the muffins in a sealed container. They will keep for 4 - 5 days. They also freeze very well.