Preheat the oven to 350°F and line a muffin tin with 12 liners.
In a medium-sized bowl, whisk together the flour, quick oats, cinnamon, baking soda, and baking powder. Set aside.
1 cup flour, 1 cup quick oats, 2 tsp cinnamon, 1 tsp baking soda, 1 tsp baking powder
Into another larger bowl, add the ripe bananas and mash with a fork until there are no large banana clumps. Make sure the bowl is large enough for all the ingredients for later.
3 large bananas
Add in melted butter, milk, and white sugar, and continue whisking.
1/3 cup melted butter, 1/4 cup milk, 1/2 cup white sugar
Add in eggs and vanilla and whisk for 2-3 minutes until the batter is light in colour and slightly frothy.
2 eggs, 2 tsp vanilla
Add the dry into the wet and gently fold using a spatula. The mixture will be thin. Do not overmix!
Toss in the mini chocolate chips and mix.
1/2 cup mini chocolate chips
Divide evenly between the 12 liners. The batter should go all the way to the top.
Sprinkle extra mini chocolate chips on top (optional).
Bake for 20-22 minutes until the top is golden brown and the muffins have risen and domed. A toothpick placed in the centre should come out clean.
Turn off your oven and slightly open your oven door. Allow the hot air to escape like this for 10 minutes. Then, remove the pan from the oven and allow the muffins to cool on the counter. If you remove the muffins from the oven right away, they will drop!
Leave on counter for 1-2 days, store in a bag on the counter for up to 4 days, or freeze in an airtight container for up to 1 month! Enjoy!