Preheat the oven to 350 degrees. Spray an 8 inch square pan with non-stick spray.
In a small bowl, whisk together the flour, cocoa powder, and salt. Set aside.
Combine the mashed bananas and sugar into a large mixing bowl of a stand mixer or use an electric hand mixer and stir until the sugar is dissolved.
Add the applesauce, vanilla and egg stirring to combine.
Add the flour mixture to the batter and combine.
By hand, fold in the chocolate chips and pour cake batter into the prepared baking pan.
If desired, sprinkle mini chocolate chips over the top and bake for 25-30 minutes.