Line a muffin pan with 15 parchment cupcake liners.
Preheat the oven to 350 F/177 C.
In a large mixing bowl, combine oats, oat flour, flax meal, cinnamon, and salt. Stir to combine.
Mash or puree the bananas. Ideally, use those that are overripe, using a food processor or immersion blender. This should come out to about 1 1/3 cups / 300 grams of mashed banana.
Add the banana, brown rice syrup (see note), raisins, and chocolate chips (if using). Stir until thoroughly combined. Note: Don’t substitute maple syrup for brown syrup; it’s not thick or sticky enough. Use overripe (freckled) bananas. Not only are they more digestible, they also offer a great deal of natural sweetness. Using a cookie scoop, place 1/4 to 1/3 cup / 60 to 80 milliliters of the batter in each muffin cup. Use a spatula or your fingers to lightly pack in the mixture. (Dampen your fingers to make it easier.)
Bake for 20 minutes.
Remove and let cool in the pan for about 5 minutes, and then transfer to cooling rack.
Enjoy warm or cooled. Store in an airtight container in the fridge.