Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) and grease a 6-ounce oven-safe ramekin.
Place oats, banana, milk, cocoa powder, maple syrup, baking powder, and salt into a high-speed blender.
Blend on high speed for 30 to 45 seconds until the batter reaches a smooth, liquid consistency.
Pour the batter into the prepared ramekin.
Sprinkle chocolate chips on top or gently fold them into the batter.
Bake for 20 to 25 minutes until the top is firm to the touch and the oats have risen.
Remove from oven and let rest for 5 minutes before serving.