Heat the oven to 350°F (180°C) and grease or line a mini muffin tin with liners.
In a large bowl, stir together the bananas, olive oil, milk, and maple syrup.
Sift in the flour, baking powder, baking soda, cinnamon, and salt. Gently fold together until combined. Add chocolate chips if using.
Pour the batter into muffin cups until almost full, about 2/3 the way up the cup.
Place in the oven and bake for 15-20 minutes or until golden brown and a tester inserted in the middle of a muffin comes out mostly clean. Remove and let cool on a wire rack.