Pre-heat oven to 350 degrees. Lightly grease a muffin pan, set aside.
Mix lemon juice and soy milk in small bowl and set aside.
Whisk dry ingredients in a bowl (flours, oats, baking powder, salt, cinnamon), set aside.
In another bowl add butter, sugars, mashed banana and mix with an electric mixer on low speed for about a minute or two. Next whisk in the soy milk/lemon, and vanilla. Whisk together until mixed.
Add dry ingredients to wet ingredients and stir until just combined (you don't want to over mix). Gently fold in the chocolate chips. Batter will be thick. Spoon into muffin tins and bake for 20-25 minutes.