In a large bowl, mix together sourdough starter, honey, melted butter, and flour.
Cover and allow to ferment for 12-24 hours (optional).
After the muffin batter has fermented, preheat the oven to 350, line or grease the muffin tins.
To the batter, add mashed banana, eggs, vanilla, salt, baking soda and baking powder.
Using the paddle attachment on the stand mixer, mix together ingredients on low to medium speed until everything is combined well.
Pour into muffin tins and bake for 18-25 minutes, or until they start to turn golden brown. They are done when a toothpick or knife inserted into the middle of the muffin comes out clean.