Preheat oven to 350 degrees. Place 18 cupcake papers in your muffin tins.
In a large bowl, whisk together the banana, sourdough starter, oil, brown sugar, white sugar, egg and vanilla until well combined.
In a second bowl, stir together the flour, baking soda, baking powder, salt, and cinnamon.
Add dry ingredients to wet ingredients and mix until just combined and there are no streaks of the flour mixture left. When it is almost completely combined, fold in the peaches. Be sure not to overman .
Pour batter into prepared muffin tins. Bake for 18 minutes or until cooked through and a toothpick comes out clean.
Cool for a few minutes in the tins, then remove and place on a wire rack to cool completely.