Pre-heat the oven to 350 F (177 C).
Mash the bananas up really well.
In a large mixing bowl, mix together the mashed bananas, water, vanilla extract, brown sugar, baking powder, baking soda, salt, cinnamon and nutmeg (everything except for the powdered sugar and vital wheat gluten).
Once this is well mixed, add in the vital wheat gluten and combine. Do NOT over-mix this, or you will end up with a chewier texture. The dough should be a little loose but able to form a cookie shape. The dough should not be wet and sloppy - if it is, add a bit of extra vital wheat gluten until the dough looks like the picture shown in the detailed instructions below.
Measure out the powdered sugar in a bowl.
Using a 2 tbsp scooper, roll the dough into balls and then toss them around in the powdered sugar. This step is optional but I do think it makes the cookies a little bit more moist and tasty :)
Place the cookies on a parchment paper-lined baking sheet.
Cook for 17 - 19 minutes.