- Preheat the oven to 375 degrees. Butter a standard muffin tin, or line with cupcake liners.
- In a large bowl, whisk together the flour, oats, baking powder, baking soda and salt. In a medium bowl, mash the bananas, then whisk in the buttermilk, sugar, oil, egg, and vanilla extract.
- Pour the wet ingredients into the flour mixture, and whisk just until blended.
- Remove one cup of the batter, and add it to a medium bowl. Whisk in the cocoa powder, just until blended.
- Divide the main (non-chocolate) batter between muffin cups. It’s about 1/4 cup of batter per cup.
- Scoop 1 tablespoon of chocolate batter on top of the batter in each muffin cup.
- Using a toothpick, swirl the chocolate batter into the banana batter.
- Bake for about 20 minutes, until a toothpick inserted into the center comes out clean. Allow to cool for about five minutes.
¼ tsp. cinnamon