If you are the proud owner of a few overripe bananas, these chocolate-studded muffins are one of the best bang-for-your-buck treats you'll find. They come together in one bowl in about half an hour, and packing them with mashed banana and Greek yogurt keeps them exceptionally soft and tender. There is just enough chocolate added to give them a little flavor boost without being totally overpowering.
You could even stir in 1/2 cup of toasted chopped walnuts for more flavor and texture.
Summary from source