Note
Well ripened bananas work best for these muffins.
When you puree the bananas, make sure there are no pieces of the fruit remaining. Else you will not get a spongy texture.
Since bananas turn brown, puree them just before you use them.
Use the high rack of your oven to bake muffins during last 3 to 5 mins of baking to get a well browned crust.
Sometimes the batter may be too thick incase the bananas are dry. In that case, add just a few tsps of water to get the right thick consistency.