Preheat the oven to 180 degrees and grease a muffin pan with nonstick cooking spray.
Place 1 ½ cups of oats in a blender or food processor and blend until a flour-like consistency forms. Set aside.
In a large bowl, mash bananas until smooth.
Add eggs, brown sugar, yogurt, and vanilla. Mix to combine.
Add ground oats, regular oats, baking powder, baking soda, and cocoa powder. Mix to combine and allow batter to rest for 10 minutes.
Fold in the chocolate chips.
Scoop batter into the muffin tin and sprinkle with additional oats, if desired.
Bake for 20 minutes or when a toothpick inserted in the center comes out clean.
Cool for a few minutes in the pan, then remove muffins to a wire rack to cool completely.