Preheat your oven to 350°F (175°C). Grease an 8x8-inch baking dish.
In a mixing bowl, combine oats, cocoa powder, baking powder, and salt.
In a separate bowl, whisk together milk, maple syrup, eggs, vanilla extract, and banana.
Pour the wet ingredients into the dry ingredients and mix until combined.
Pour the mixture into the prepared baking dish and spread evenly. Sprinkle chocolate chips on top.
Bake for 25-30 minutes or until set and slightly puffed.
Let cool for 5 minutes before slicing and serving.