Preheat the oven to 350°F. Lightly grease a loaf pan and set aside.
In the bowl of a stand mixer, cream together the butter and sugars until light and fluffy. Add in the egg, mayonnaise and bananas, and mix until fully combined.
In a separate bowl, mix together the flour, salt, baking powder and baking soda. Slowly mix the dry ingredients into the wet ingredients, and mix until just combined.
Fold in the chocolate chips.
Bake in the preheated oven for 60-70 minutes, or until a toothpick inserted comes out clean. Allow the loaf to cool in the pan for 10 minutes before removing and transferring to a wire rack to cool completely.