1Preheat oven to 375 degrees F (190 degrees C). Grease 12 muffin cups or line with paper liners.
2Whisk 1 1/2 cup flour, baking soda, baking powder, and salt in a bowl. Beat bananas, 3/4 cup brown sugar, agave syrup, egg, and 1/3 cup applesauce in a separate bowl until thoroughly combined. Stir banana mixture into the dry ingredients to make a smooth batter. Fill muffin cups about 2/3 full of batter.
3Mix 1/3 cup brown sugar, 2 tablespoons flour, and cinnamon in a bowl; stir 1 1/2 teaspoons of applesauce into the mixture until it resembles coarse crumbs. Sprinkle topping over muffins.
4Bake in the preheated oven until lightly golden brown and a toothpick inserted into center of a muffin comes out clean, 18 to 20 minutes.
Footnotes
Cook's Note:
Since packed brown sugar is not as sweet as white sugar, I added a tablespoon of agave honey/syrup. The bananas were very ripe (the skin was already brown) so if the bananas you have are not that ripe, you might want to add more agave syrup. I live in Yucatan's peninsula so preheated the oven at 150°C. If you live in a non-altitude place you might have to bake 20°C to 30°C less than what the recipe calls for.
Tip
Aluminum foil helps keep food moist, ensures it cooks evenly, keeps leftovers fresh, and makes clean-up easy.