In a large bowl, add the mashed banana, milk, sugar, sourdough discard, eggs, butter, vanilla, salt, baking powder, and baking soda, and whisk to combine.
Add the flour and whisk it in; it’s okay if it’s a bit lumpy.
These can be cooked right away, or you can cover the bowl and refrigerate it overnight (or up to 24 hours).
When ready to cook, preheat a cast-iron or non-stick pan over medium heat and grease it with butter.
Ensure the pan is hot and the butter is sizzling, then pour in around 1/4 cup of batter for each pancake. If the pan gets too hot, turn down the heat a little once you've poured in the batter. The banana in the pancake can cause these to burn easily if it gets too hot.
Cook the pancake for around 2-3 minutes until bubbles appear on the surface. Flip the pancake over and cook the other side for another minute or 2.
Transfer the pancake to a plate and continue with the rest of the batter until it is all used up, stacking the pancakes in a pile as you go.
Serve with banana, berries and maple syrup.