Preheat the oven to 325 ° F.
Add the mashed banana and sugar to a bowl and whisk with an electric mixer until incorporated.
Add melted butter, eggs and vanilla extract and mix.
Add flour, baking powder, baking soda and salt to the batter and mix until just incorporated. (Make sure to not over mix!)
Using a spatula, fold in the chocolate chips and then scoop batter into a into a zip lock bag and seal shut. Snip one of the bottom corners with scissors to create a homemade piping bag.
Grease your donut baking pan and fill 3/4 full with batter into each mold.
*Garnish with cinnamon sugar on top of each donut before baking or after baking paint with melted butter before sprinkling with cinnamon sugar to make sure it sticks!
Bake for 12 to 15 minutes. Remove from pan and allow to cool before eating.