Preheat your oven to 400°F and line a standard 12-cup muffin pan with paper liners.
In a medium bowl, whisk together flour, baking powder, baking soda, ground cinnamon and salt until evenly blended.
Mash the bananas with a fork on a flat surface (like a clean cutting board or a plate) until very smooth. Add it to a large mixing bowl.
Add brown sugar to the mashed bananas and mix well. Add eggs and whisk until smooth.
Add oil, yogurt, milk and vanilla and whisk until combined.
Add oats and mix them in, then let the batter rest for 5 minutes to let the oats hydrate.
Add dry ingredients all at once and fold it all in gently with a spatula until just combined. Do not over-mix.
Fold in chocolate chips until evenly distributed.
Divide batter evenly among prepared muffin cups, filling them to the rim. Sprinkle extra oats on top.
Bake for 5 minutes at 400°F. Reduce oven temperature to 375°F and bake for 15-18 minutes longer until golden brown and slightly firm to the touch.
Transfer pan to a wire rack and let muffins cool for 5 minutes before transferring individually to the rack to finish cooling.