Preheat oven to 350 degrees. In a large bowl, whisk together the protein powder, oats, cacao powder, coconut sugar, and baking powder.
In a smaller bowl, mash the banana with a fork, and whisk together with the eggs, coconut oil, and milk.
Pour the wet ingredients into the dry ingredients, and use a wooden spoon to mix until there are no clumps. Then, add the chocolate chips and give it one more stir.
Spray a muffin tin with cooking spray, then spoon the batter into the muffin tin until each muffin is 3/4 of the way full. Bake for 25-30 minutes, or until when you can stick a butter knife in the center and it comes out clean.
Let them cool for at least 5 minutes before removing them from the pan.