1. Preheat oven to 425 degrees Fahrenheit. Line a muffin pan with liners (I use parchment liners) and set aside.
2. In a bowl, mix together bananas, eggs, oil, maple syrup/honey, vanilla, and Greek yogurt/milk.
3. Add flour, oats, cocoa powder, baking powder, baking soda, cinnamon, and salt. Mix until just combined. Fold in chocolate chips.
4. Spoon about one-quarter cup of batter into each muffin liner. Bake at 425 degrees for eight minutes. Reduce temperature to 375 degrees and bake for about eight more minutes, or until a toothpick inserted in the center comes out clean.