Preheat oven to 350℉. Line a large baking sheet with parchment paper.
In a large mixing bowl, sift in 2 cups of the oat flour, baking powder and salt and whisk together until combined. Add in the mashed bananas and mix with a spatula or preferably your hands, until incorporated. Your dough will be very sticky. Add in 1 tbs of the remaining flour and knead in. Then repeat with the remaining flour. Form a large disc shaped ball and then divide the dough into 8 equal pieces. Roll them into 8 balls, place onto the baking sheet, optionally sprinkle tops with rolled oats and bake for 18-20 minutes or until light golden brown on top.