Preheat the oven to 400 degrees F and line an 8x8-inch metal baking pan. Set aside.
Add the banana, eggs, milk, butter, and vanilla to a medium bowl. Whisk smooth.
Add the flour, sugar, cinnamon, baking powder, baking soda, and salt to the bowl. Stir gently with a spatula or spoon to combine thoroughly.
Pour into the prepared pan and top with the chocolate chips.
Bake for 22-26 minutes, or until golden brown around the edges and a cake tester inserted into the center comes out clean. Let cool in the pan for 5 minutes, then transfer the cake (using the parchment paper) to a wire rack to cool fully. Slice into bars and serve.
