Preheat the oven to 350°F then grease a standard size loaf pan.
In the bowl of a blender, combine the bananas, milk, vinegar, coconut sugar and vanilla extract. Blend on high for 15-20 seconds until a smooth frothy liquid forms. Alternatively you can use an immersion blender or mash everything together by hand. I recommend using a blender for best results. Pour the liquid into a large bowl, add the melted coconut oil and set aside.
In a separate large bowl, whisk together the oat flour, almond flour, cinnamon, baking powder, baking soda and salt. Make sure to whisk or sift any lumps of flour.
To the bowl with the liquid ingredients, add the dry in 4 separate parts, stirring in between. This will assure the flour is incorporated as evenly as possible. Lastly, stir in the chocolate chips.
Transfer the batter to your greased loaf pan and arrange a few more chocolate chips on top. Bake in the oven for approximately 45 minutes. The bread should be firm and golden brown. Allow to cool completely before slicing and serving. I know it's tempting to eat it right away but the texture will improve as it cools.
Be sure your bananas are big enough to equal 1 cup worth when mashed. Very ripe bananas work best.