Preheat the oven to 350°F and prepare your loaf pan. Cut a parchment paper sling slightly smaller than the width of the pan and make sure it fits flatly in the bottom. Then lightly spray the bottom and sides of the pan with a vegetable oil based spray. Place you parchment paper sling in the bottom of the pan and smooth it out so that it sticks to the pan spray.
In a large bowl, whisk together the melted butter, brown sugar, egg, and vanilla until fully combined and smooth.
Add in the sourdough discard, mashed banana, and milk and whisk until fully incorporated. The batter will be lumpy, that's okay.
Add in the flour, baking powder, and salt and fold until just combined.
Gently mix in the chocolate chips and pecans.
Pour the batter into your prepared loaf pan and top with extra chocolate chips and pecans if desired.
Bake at 350°F for 45-50 minutes or until a cake tester comes out *mostly* clean (you don't want thick wet batter, but a few moist crumbs is okay).
Remove from the oven and let cool in the pan for at least 10 minutes before slicing.
Notes
Wrap the banana bread in plastic wrap or aluminum foil and store at room temperature for up to 4 days.You can easily make this sourdough banana bread into muffins! Simply line a muffin pan with muffin liners, and reduce the baking time to 25-30 minutes! This recipe will make about 12 muffins.I highly recommend actually measuring out your mashed banana so that you don't end up with too much or too little. If you don't have enough banana, you can replace the rest with applesauce or sour cream!If you're feeling fancy, I also recommend substituting the butter for brown butter for an rich, nutty depth of flavor!