1Preheat oven to 350 degrees F (175 degrees C). Grease 12 muffin cups or line with paper liners.
2Mash bananas and sugar together in a bowl; add egg and vanilla extract and mix well. Stir whole wheat flour, baking powder, baking soda, and salt together in a separate bowl; stir into banana mixture just until batter is mixed. Stir oil into batter and fold in cranberries. Spoon batter into the prepared muffin cups.
3Bake in the preheated oven until a toothpick inserted in the center comes out clean, 22 to 26 minutes.
Footnotes
Cook's Notes:
Variations: replace cranberries with fresh or frozen blueberries, 1/2 cup chopped nuts, 1/2 cup chocolate chips, 3/4 cup raisins, etc.
Brown sugar can be used in place of the white sugar. All-purpose flour can be used in place of the whole wheat.
This can also be baked in a loaf pan for 50 to 60 minutes.
Tip
Parchment can be used for easier cleanup/removal from the pan.