Preheat the oven to 425° F. Grease muffin pan with non-stick spray or line with cupcake liners. Set aside.

For buttermilk, add white vinegar into a room temperature milk, mix well, and set aside.

Sift flour, baking powder, baking soda, salt, and ground cinnamon together. Whisk well and set aside.

In a large mixing bowl, take mashed bananas. You can mash bananas either with a fork or blend them into a blender. You can also use a stand mixer with a paddle attachment to mash bananas.

Add melted butter, brown sugar, and vanilla. Mix until everything is well combined.

Now add flour mixture and buttermilk. Mix until combined. Do not overmix.

Fold in chocolate chips into the batter and mix gently to distribute evenly.

Spoon the batter into the muffin pan, filling each tin all the way to the top.

Bake for 5 minutes at 425° F and then, keeping the muffins in the oven, reduce the oven temperature to 350° F. Continue baking for 13-14 minutes or until the toothpick inserted in the center comes out clean.

Remove the muffins from the oven and let them cool in the pan for 5 minutes. Then transfer onto a cooling rack and let it cool completely before serving.