1. Preheat oven to 350 degrees F. Lightly grease muffin tin or use muffin liners.
2. In a large bowl, combine butter and brown sugar. Mix until smooth. (About a minute with a hand mixer)
3. Add in mashed bananas, honey, eggs, vanilla, sourdough discard, baking soda, baking powder and sea salt. Mix until smooth. There may still be chunks of banana in the batter.
4. Add flour. Mix until just combined. Add in the extras if you are using any.
5. Spoon into muffin tin. You will use all the batter to fill all 12 muffin cups. This may make them seem plenty full, but it will be ok.
6. Let the batter sit in the pan for 5-10 minutes.
7. Bake at 350 degrees F for 20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
8. Allow to cool and remove from pan.