Preheat oven to 350°F (180°C). Line two 12-hole mini muffin trays with oil spray. Set them aside.
Peel, mash the bananas with a fork and measure 1/2 cup - precision is important to avoid gummy muffins.
Place the mashed bananas in a large mixing bowl and combine with applesauce, melted butter, milk, and lemon juice.
Stir in the remaining dry ingredients: flour, quick oats, baking powder, baking soda, and shredded carrots.
Fill the muffin holes with about 1-2 tablespoons of batter.
Bake in the center rack of the oven until golden-brown, and a pick inserted in the center of the baby muffins comes out clean - about 15-18 minutes.
Cool them down immediately on a wire rack.
Serve plain or with fruits and yogurt on the side.