Leftover muffins can be frozen for up to two weeks.
Preheat oven to 375º.
Combine bananas and next 4 ingredients (through vanilla) in a medium bowl; mix well, and set aside.
Lightly spoon flour into a dry measuring cup and level with a knife. Whisk together flour and next 5 ingredients (through salt) in a small bowl.
Stir the flour mixture into the banana mixture until they are just combined.
Spray 9 muffin cups with cooking spray (or use paper liners), and spoon 1/3 cup batter into each cup (cups will be full).
Bake 16 minutes or until a wooden pick inserted in center comes out clean.