In a medium bowl, add the flour, baking soda, baking powder, and salt. Mix until fully combined.
In a large mixing bowl, add the bananas. Mash well until a puree forms.
Add the starter, milk, eggs, vanilla extract, and melted butter. Mix well.
Add the dry ingredients to the wet ingredients. Mix until just combined, it's ok if there are a few lumps left in the batter.
Preheat a nonstick pan and add 1 tablespoon of butter to the pan. When the butter is melted, add a scoop of the batter to the pan.
With the heat on medium to medium high heat, cook the pancakes. When the outside of the pancakes start to look dry and there are bubbles in the middle of the pancake, carefully flip the pancake over.
Let the other side cook for 2-3 minutes until both sides are golden brown. Repeat this process for the rest of the pancakes.