Preheat the oven to 410 °F (210 °C) and line 2 muffin pans with 16 liners.

To a 1-cup measuring cup, add 1 tablespoon vinegar. Fill it up with the milk. Let sit for 5 minutes to thicken.

In a medium mixing bowl, stir together the dry ingredients (flour, baking powder, baking soda, salt and cinnamon). Set aside.

To a large mixing bowl, stir together the thickened milk, mashed bananas, brown sugar, oil and vanilla extract. Stir until combined. It’ll look weird and oily, and that’s fine.

Fold the dry ingredients into the wet, and stir until combined and no large lumps remain.

Fold in the chocolate chips.

Using a 1/3 cup measure, scoop 83 grams of the batter (which will be a bit under 1/3 cup) into the muffin liners.

Sprinkle each muffin top with 1 tablespoon mini chocolate chips.

Bake for 5 minutes at 410 °F (210 °C) and then at 375 °F (190 °C) for an additional 10-14 minutes (I did 12). A toothpick inserted in the middle should come out clean.

Place the muffin pans on a wire rack to cool for 5 minutes, and then turn the muffins out onto the rack to cool completely, about 30 minutes to 1 hour. If making the gluten-free version, it's important to let them cool almost completely so that they're not gummy, dense, etc.

Store at room temperature in an airtight container for up to 3 days, refrigerate for up to a week or freeze for up to 3 months.