Preheat oven to 375℉. Prepare mini muffin pan(s) by greasing with nonstick baking spray or lining with mini muffin liners. Melt one stick (½ cup) of unsalted butter and set aside.
In a bowl, whisk together flour, baking soda, cinnamon, and salt. Set aside.
Next, mash the ripe bananas - they should be super easy to mash up, that's how you know they are ready! Measure out 285g after they are mashed to ensure you have the right amount.
Tp the mashed bananas, add in the melted butter, brown sugar and sugar, whisking until combined. Then whisk in the eggs and vanilla extract.
Fold in the flour mixture until combined and then fold in the mini chocolate chips. Avoid overmixing!
Scoop a little over a tablespoon into each mini muffin well and bake in the oven for 12-14 minutes. Muffins are done when baked through and they have a perfect little muffin dome with a lightly golden top and golden brown around the edges.
Let the mini banana muffins cool for around 5-10 minutes in the pan before releasing them by using a fork or butter knife slid down the side of the muffins to pop them out! Cool completely on a cooling rack or plate.
Store in an airtight container or bag. Enjoy!