Preheat oven to 325˚F. Grease a 24-cup mini muffin tin with cooking spray and set aside.
In the bowl of a stand mixer, add mashed banana, sugar and greek yogurt. Beat until incorporated. Beat in melted butter, eggs, vanilla and peanut butter.
Gradually add in flour, baking powder, baking soda, and salt, mixing until just incorporated. Fold in mini chocolate chips.
Spoon batter into prepared mini muffin pan, filling the cups about 3/4 of the way full.
Bake for 12 to 15 minutes. Cool in the pan for 5 minutes.
Remove from pan and allow to cool on a wire rack before eating.