Preheat the oven to 375°F. Lightly spray a muffin pan with cooking spray and set aside.
In a large bowl, beat together the banana, sugar, egg and applesauce.
In a separate bowl, mix together the flours, cocoa, salt, baking soda and baking powder. Add into the wet ingredients, and miix until just combined.
Fold in the chocolate chips.
Divide the batter evenly into the prepared muffin pans, and bake in the preheated oven for 18-20 minutes, or until a toothpick inserted comes out clean. Allow to cool in the pan for around 5 minutes, then transfer to wire racks to cool completely.