In a stand mixer with the paddle attachment, mix the bananas and brown sugar until the bananas are mashed and the sugar is dissolved.
Add the applesauce, vanilla, and egg. Mix together.
In a separate bowl, mix together the flour, cocoa powder, baking soda and salt. Add the dry ingredients to the wet ingredients and mix until incorporated.
Fold in the semi-sweet chocolate chips. Pour batter into a greased 8x8-inch baking dish. Sprinkle the top with mini chocolate chips.
Bake at 350 degrees Fahrenheit for 25 to 35 minutes. Check the center with a toothpick to determine doneness. Best eaten warm.
Video
Notes
You can substitute any neutral tasting oil for the applesauce.