Preheat oven to 350F and line a muffin tin with liners and nonstick spray.
Make homemade oat flour by grinding oatmeal in a blender, measuring after blended.
In a large bowl, whisk mashed banana, coconut oil, eggs, peanut butter, maple syrup, and vanilla until well combined.
In a small bowl, mix oat flour, cocoa powder, baking powder, baking soda, and salt.
Add dry ingredients to wet and stir until combined. Stir in chocolate chips.
Pour into muffin tin about 3/4 the way full, add more chocolate chips on top, and bake for about 18-20 minutes or until toothpick inserted comes out clean.
Enjoy!